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Photo description: Composite image of the galaxy NGC 1068Large 2400 x 2462 (300)
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NGC 1068: Wind and reflections from a black hole

This composite X-ray, shown in blue and green, and optical, shown in red, image of the active galaxy, NGC 1068, shows gas blowing away in a high-speed wind from the vicinity of a central supermassive black hole. Regions of intense star formation in the inner spiral arms of the galaxy are highlighted by both optical and X-ray emission.

The elongated shape of the gas cloud is thought to be due to the funneling effect of a torus, or doughnut-shaped cloud, of cool gas and dust that surrounds the black hole. The torus, which appears as the elongated white spot in the accompanying three-color X-ray images, has a mass of about 5 million Suns. Radio observations indicate that the torus extends from within a few light years of the black hole out to about 300 light years.

The X-rays observed from the torus are scattered and reflected X-rays that are probably coming from a hidden disk of hot gas formed as matter swirls very near the black hole. The torus is one source of the gas in the high-speed wind, but the hidden disk may also be involved. X-ray heating of gas further out in the galaxy contributes to the slower, outer parts of the wind.

Observations with the spectrometers aboard NASA's Chandra X-ray Observatory enable scientists to estimate the composition, temperature and flow velocity of the gas. They show that the composition of the material in the wind is roughly similar to that of the Sun's atmosphere, except for a deficit of oxygen atoms, and that it has a temperature of about 100,000 degrees Celsius (180,000 degrees Fahrenheit). The average gas speed is about 1 million miles per hour.

These Chandra data on NGC 1068 are consistent with a picture where the observer is looking along the edge of a torus of cool gas and dust around a supermassive black hole. In this case we see the indirect effects of the black hole, but do not get a direct view. In contrast, an observer looking down into the hole of the torus would see a brilliant black hole source (see NGC 5548, NGC 4151).

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (Credit - X-ray: NASA/CXC/MIT/UCSB/P.Ogle et al.; Optical: NASA/STScI/A.Capetti et al.)

Reference: P. Ogle et al. 2003 Astronomy and Astrophysics, 402, 849

The image and additional information are available at:

http://chandra.harvard.edu/
and
http://chandra.nasa.gov/


Photo description: Chandra image of the Vela pulsarLarge 2271 x 1821 (300)
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Chandra X-ray Observatory image of the Vela Pulsar: Firehose-like jet observed in action

The NASA Chandra X-ray Observatory images in this montage show the erratic variability of a jet of high-energy particles that is associated with the Vela pulsar, a rotating neutron star. These images are part of a series of 13 images made over a period of two and a half years that has been used to make a time-lapse movie of the motion of the jet.

Much like an untended firehose, the jet bends and whips about spectacularly at half the speed of light. Bright blobs move in the jet at similar speeds. The jet is half a light year, or three trillion miles, in length and is shooting out ahead of the moving neutron star. The extremely high-energy electrons or positrons that compose the jet were created and accelerated by the combined action of the fast rotation of the neutron star and its intense magnetic field. These particles produce X-rays as they spiral outward around the magnetic field of the jet.

Over its entire length, the width of the jet, about 200 billion miles, remains approximately constant. This suggests that the jet is confined by magnetic fields generated by the charged particles flowing along the axis of the jet. Laboratory studies of beams of particles confined in this manner have shown that they can change rapidly due to an effect called the "firehose instability." This is the first time such behavior has been observed in astrophysical jets.

To picture how the firehose instability works, imagine a firehose lying on the ground. When the water is turned on, different parts of the hose will kink and move rapidly in different directions, pushed by the increased pressure at the bends in the hose. The Vela jet resembles a hose made of magnetic fields, which confines the charged particles. The bright blobs in the jet are thought to be a manifestation of the increased magnetic field and particle pressure at the kinks in the jet.

The instability could be triggered by the strong headwind created as the pulsar moves through the surrounding gas at a speed of about 200,000 miles per hour. The activity of the Vela pulsar jet could also help to understand the nature of the enormous jets coming from supermassive black holes. Those jets may also vary, but on time scales of millions of years, instead of weeks as in the Vela pulsar jet.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/CXC/Penn State/G. Pavlov et al.)


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Chandra X-ray Observatory Deep Field North

The Chandra X-ray Observatory Deep Field North image was made by observing an area of the sky one-fifth the size of the full moon for 23 days. It is the most sensitive or "deepest" X-ray exposure ever made. The faintest sources produced only one X-ray photon every four days.

More than 500 X-ray sources are present in this high-energy core sample of the early universe. Most of the sources are supermassive black holes located in the centers of galaxies. If the number of supermassive black holes seen in this patch of the sky is typical, the total number detectable over the whole sky at this level of sensitivity would be 300 million.

By combining the Chandra and Hubble data for this field, astronomers can take a census of the fraction of young galaxies that contain active supermassive black holes back to a time when the universe was only about one billion years old, less than 10 percent of its present age. The data show that these very distant supermassive black holes are rare, more so than expected.

The data indicate that it takes about 700 million years for a supermassive black hole to accumulate the millions of solar masses of gas needed to produce a powerful X-ray source. The relatively slow growth of the supermassive black holes may be due to a reduced gas supply created when early generations of massive stars exploded as supernovas and blew gas out of the galaxies.

However, it is possible that a few supermassive black holes could have formed earlier. Seven mysterious sources have been detected by Chandra, but not by the Hubble Space Telescope. These sources, which are likely supermassive black holes, have also been detected in infrared.

The optically invisible sources could be central black holes in unusually dusty galaxies where the optical radiation is absorbed by the dust. Or, the mysterious sources could be candidates for the most distant galaxies ever observed. In the latter case, the red shift due to the expansion of the universe has shifted the optical radiation to infrared wavelengths, and we are seeing them as they were when the universe was only about 500 million years old.

The detection of most of the mystery sources at infrared wavelengths is consistent with either explanation. Further observations at X-ray, optical and infrared wavelengths will be needed to determine the exact nature of these objects.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/CXC/Penn State/D.M. Alexander, F.E. Bauer, W.N. Brandt et al.)


Photo description: Chandra image of the galaxy cluster Abell 2029Large 2263 x 1208 (300)
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Chandra image of the galaxy cluster Abell 2029

The galaxy cluster Abell 2029 is composed of thousands of galaxies, shown in the optical images, right, enveloped in a gigantic cloud of hot gas, shown in the X-ray image, left, and an amount of dark matter equivalent to more than a hundred trillion Suns. At the center of this cluster is an enormous, elliptically shaped galaxy thought to have been formed from the mergers of many smaller galaxies.

The Chandra X-ray Observatory image shows a smooth increase in the intensity of X-rays all the way into the central galaxy of the cluster. These X-rays are produced by the multi-million degree gas, which is confined to the cluster primarily by the gravity of the dark matter. By precisely measuring the temperature and intensity distribution of the X-rays, astronomers were able to make the best map yet of the distribution of dark matter in the inner region of the galaxy cluster.

The X-ray data imply that the density of dark matter increases smoothly all the way into the central galaxy of the cluster. This discovery agrees with the predictions of cold dark matter models, and is contrary to other dark matter models that predict a leveling off of the amount of dark matter in the center of the cluster.

If Abell 2029 is a representative sample of the universe, these results indicate that 70 to 90 percent of the mass of the universe consists of cold dark matter -- mysterious particles left over from the dense early universe that interact with each other and "normal" matter only through gravity. Cold dark matter gets its name from the assumption that cold dark matter particles were moving slowly when galaxies and galaxy clusters began to form. The exact nature of these particles is still unknown.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (X-ray: NASA/CXC/UCI/A. Lewis et al.; Optical: Pal.Obs. DSS)


Photo description: Artist's conception of TW Hydrae, left, and HD 98800A, right.Large 2400 x 2400 (300)
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The striking Chandra X-ray Observatory image of supernova remnant, SNR 0103-72.6, reveals a nearly perfect ring about 150 light years in diameter surrounding a cloud of gas enriched in oxygen and shock-heated to millions of degrees Celsius. The ring marks the outer limits of a shock wave produced as material ejected in the supernova explosion plows into the interstellar gas. The size of the ring indicates that we see the supernova remnant as it was about 10,000 years after its progenitor star exploded.

Scientists have known for years that oxygen and many other elements necessary for life are created in massive stars and dispersed in supernova explosions, but few supernova remnants rich in these elements have been observed.

SNR 0103-72.6 is in the Small Magellanic Cloud (SMC) about 190,000 light years from Earth. The X-rays take about 190,000 years to reach us from the SMC, so the supernova explosion occurred about 200,000 years ago, asmeasured on Earth. One of the closest galaxies to the Milky Way galaxy, the SMC is visible to the naked eye from the Southern Hemisphere. This supernova remnant will become an important laboratory for studying how stars forge the elements necessary for life. Although SNR 0103-72.6 is more distant than supernova remnants in our Galaxy, scientists have a clear view of it because its light is not blocked by the dusty spiral arms of the Milky Way. (NASA/CXC/Penn State/S. Park et al.)


Photo description: Artist's conception of TW Hydrae, left, and HD 98800A, right.Large 2236 x 1292 (300)
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An artist's conception shows TW Hydrae, left, and HD 98800Aright, two young star systems that are members of the TW Hydrae stellar association, which formed about 10 million years ago. Observations of their X-ray spectra by the Chandra X-ray Observatory revealed that, although both stars were formed in the same region of space at the same time, they produce X-rays by different mechanisms.

The insets show portions of the X-ray spectra for each system. Of particular interest are the peaks labeled r, i and f. These peaks, due to X-rays from neon atoms that have lost all but two of their 10 orbital electrons, are sensitive indicators of the density and temperature in the hot, X-ray emitting gas in the star systems.

The relative sizes of the peaks in TW Hydrae provide strong evidence that the matter is accreting onto the star from a circumstellar disk as shown in the illustration. X-rays are produced and matter is guided by the star's magnetic field onto one or more hot spots on the surface of the star.

In contrast, the spectrum of the binary star system HD 98800A revealed that its brightest star is producing X-rays much as the Sun does, from a hot upper atmosphere or corona. This indicates that any disk around these stars has been greatly diminished or destroyed in 10 million years, perhaps by the ongoing formation of planets or by its companion stars. (Spectra: NASA/CXC/RIT/J. Kastner et al.; Illustration: CXC/M. Weiss)


Photo description: Chandra image of the galaxies NGC 4485 and NGC 4490Medium 500 x 500 (72)
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Chandra X-ray Observatory image of the galaxies NGC 4485 and NGC 4490

NGC 4485 and NGC 4490 are two of the 90 galaxies surveyed in a study of the ultra-luminous X-ray source (ULX) population of nearby galaxies. This image, taken with the Advanced CCD Imaging Spectrometer onboard NASA's Chandra X-ray Observatory, shows numerous bright X-ray sources within clouds of cooler gas. Five of these point-like sources are potential ULXs --- candidates for intermediate-mass black holes. Blue colors in this image represent hotter, high-energy, emission while red colors denote cooler, low-energy, X-rays.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/MSFC)


Photo description: Composite image of Stephan's QuintetLarge 2236 x 1292 (300)
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Chandra images of 4C41.17 AND 3C294:
New view of biggest construction sites in universe

Chandra X-ray Observatory images of two distant massive galaxies show they are enveloped by vast clouds of high-energy particles that are evidence for past explosive activity. In both galaxies radio and X-ray jets allow this activity to be traced back to central supermassive black holes. The jets are heating gas outside the galaxies in regions hundreds of thousands of light years across.

The Chandra data will help scientists understand how nature imposes a weight limit on the growth of the most massive galaxies in the universe. These galaxies reside in regions of space that contain an unusually large concentration of galaxies, gas and dark matter.

A massive galaxy and its central black hole grow through cannibalization of nearby galaxies and through accumulation of gas from intergalactic space. Eventually however, the infall of matter into the central supermassive black hole will produce an energetic jet, which will heat the surrounding gas and stop the growth of the galaxy at a few dozen times the mass of our Milky Way galaxy.

Another implication of this research is that a massive galaxy does not grow steadily, but in fits and starts. In the beginning of a growth cycle, the galaxy and its central black hole are accumulating matter. The energy generated by the jets that accompany the growth of the supermassive black hole eventually brings the infall of matter and the growth of the galaxy to a halt. The activity around the central black hole then ceases because of the lack of a steady supply of matter, and the jets disappear. Millions of years later the hot gas around the galaxy cools and resumes falling into the galaxy, initiating a new season of growth.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (4C41.17: NASA/CXC/Columbia/C. Scharf et al.
3C294: NASA/CXC/IoA/A. Fabian et al.)


Photo description: Composite image of Stephan's QuintetLarge 2250 x 2250 (300)
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Stephan's Quintet: Intruder galaxy shocks tightly knit group

The hurly-burly interactions in the compact group of galaxies known as Stephan's Quintet are shown in the upper left where a Chandra X-ray Observatory image, in blue, is superimposed on a Digitized Sky Survey optical image, in yellow. Shock-heated gas, visible only with an X-ray telescope, appears as a bright blue cloud oriented vertically in the middle of the image and has a temperature of about 6 million degrees Celsius. The heating is produced by the rapid motion of a spiral galaxy intruder located immediately to the right of the shock wave in the center of the image, as shown in the galaxy labeled B in the wide field optical image on the lower right.

Stephan's Quintet is an excellent example of the tumultuous dynamics of a compact group. The motion of the galaxies through the hot gas, and the gravitational pull of nearby galaxies are stripping cool gas from the galaxies, thereby depriving them of the raw material from which to form new stars. In a few billion years the spiral galaxies in Stephan's Quintet will likely be transformed into elliptical galaxies.

During the past few billion years additional gas may have been stripped from the galaxies in the group and heated by collisions such as the one seen in these images. An intruder that may have passed through the center of the group at least twice is the faint galaxy C seen in the wide field optical image. The fainter blue cloud in the X-ray/optical image may be a relic of past collisions.

The four galaxies A, B, D and E strung out diagonally across the wide field optical image are at a distance of about 280 million light years from Earth. The large-appearing galaxy F in the lower left of this image has now been identified as a foreground galaxy at a distance of about 35 million light years, leaving the group originally identified as Stephan's Quintet with only a quartet of galaxies. However, if we include galaxy C, which is at the same distance as the other four galaxies, it becomes a quintet again!

Ginevra Trinchieri of the INAF-Brera Observatory in Milan, Italy, Jack Sulentic of the University of Alabama in Tuscaloosa, and Dieter Brietschwerdt and Wolfgang Pietsch of the Max-Planck Institute for Extraterrestrial Physics in Garching, Germany are co-authors of a paper that describes the Chandra data on Stephan's Quintet. The paper will appear in an upcoming issue of the journal Astronomy & Astrophysics.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (X-ray: NASA/CXC/INAF-Brera/G.Trinchieri et al.; Optical: Pal.Obs. DSS)


Photo description: Composite image of Centaurus A JetLarge 2267 x 1758 (300)
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Centaurus A Jet: Energetic Jet Meets Resistance In Nearby Galaxy

A composite X-ray and radio image shows the inner 4,000 light years of a magnetized jet in the Centaurus A galaxy. The Chandra X-ray Observatory image is shown in blue, while the Very Large Array (VLA) radio image is shown in red. Purple regions are bright in both radio and X-ray. The jet originates from the vicinity of the supermassive black hole at the center of the galaxy, located in the lower right hand corner of the image.

The radio observations, taken between 1991 and 2002, showed that the inner portion of the jet is moving away from the center of the galaxy at speeds of about half the speed of light. Most of the X-rays from the jet are produced farther out where the jet stalls as it plows through the gas in the galaxy. The collision of the jet with the galactic gas generates a powerful shock wave that produces the extremely high-energy particles responsible for the X-rays.

Because Centaurus A Jet is relatively nearby at a distance of 11 million light years, this image offers one of the most detailed looks yet at the interaction of a jet with gas in its galaxy. Jets such as the one in Centaurus A Jet are widespread phenomena in the cosmos, and represent one of the primary means for extracting energy from the vicinity of a black hole. Some jets extend over distances of a million light years. They represent a major energy source for the galaxy and are thought to affect the evolution of the host galaxy and its surroundings. The Centaurus A Jet image will help scientists to understand the effects of jets on their environment.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (X-ray: NASA/CXC/Bristol U./M. Hardcastle et al.; Radio: NRAO/VLA/Bristol U./M. Hardcastle)


Photo description: Chandra image of the brown dwarf TWA 5BLarge 2242 x 1850 (300)
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Chandra X-ray Observatory image of the brown dwarf TWA 5B

An image from NASA's Chandra X-ray observatory revealed X-rays produced by TWA 5B, a brown dwarf orbiting a young binary star system known as TWA 5A. The star system is 180 light years from the Earth and a member of a group of about a dozen young stars in the constellation Hydra.

The brown dwarf orbits the binary star system at a distance about 2.75 times that of Pluto's orbit around the Sun. The sizes of the sources in the image are due to an instrumental effect that causes the spreading of pointlike sources.

Brown dwarfs are often referred to as "failed stars" because they are under the mass limit (about 80 Jupiter masses, or 8 percent of the mass of the Sun) needed to spark the nuclear fusion of hydrogen to helium which supplies the energy for stars such as the Sun. Lacking any central energy source, brown dwarfs are intrinsically faint and draw their energy from a very gradual shrinkage or collapse.

Young brown dwarfs, like young stars, have turbulent interiors. When combined with rapid rotation, this turbulent motion can lead to a tangled magnetic field that can heat their upper atmospheres, or coronas, to a few million degrees Celsius. The X-rays from both TWA 5A and TWA 5B are from their hot coronas.

TWA 5B is estimated to be only between 15 and 40 times the mass of Jupiter, making it one of the least massive brown dwarfs known. Its mass is rather near the boundary, about 12 Jupiter masses, between planets and brown dwarfs, so these results could have implications for the possible X-ray detection of very massive planets around stars.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/CXC/Chuo U./Y. Tsuboi et al.)


Photo description: Afterglow of the gamma-ray burst GRB 020813 Large 2400 x 2400 (300)
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Chandra X-ray Observatory image of the afterglow of the gamma-ray burst GRB 020813

A 21-hour Chandra observation of the afterglow of the gamma-ray burst GRB 020813 revealed an overabundance of elements characteristically ejected by the supernova explosion of a massive star. The afterglow is thought to be produced by the interaction of a jet of high-energy particles with the expanding supernova shell.

Narrow lines, or bumps due to silicon and sulfur ions were clearly identified in the X-ray spectrum of GRB 020813 — so named because it was discovered by the High-Energy Transient Explorer satellite on August 13, 2020. The High-Energy Grating Spectrometer aboard Chandra allowed a team of astronomers to study details of the X-ray lines. The grating disperses X-rays much like a prism disperses visible light to produce the crossed bands shown in the image below the illustration — the narrow bright regions are the spectral lines.

An analysis of the Chandra data showed that the ions were moving away from the site of the gamma-ray burst at a tenth the speed of light, probably as part of a shell of matter ejected in the supernova explosion. The line features were observed to be sharply peaked, indicating that they were coming from a narrow region of the expanding shell. This implies that only a small fraction of the shell was illuminated by the gamma-ray burst, as would be expected if the burst was beamed into a narrow cone. The observed duration of the afterglow suggests a delay of about 60 days between the supernova and the gamma-ray burst.

The data appear to support the supra-nova model for a gamma-ray burst, in which the burst occurs soon after, but not simultaneously with the supernova. The collapse of the core of an extremely massive star precipitates an explosion that ejects the outer layers of the star at high speeds, while the collapsed core forms a black hole surrounding by a swirling disk of matter.

A short time later, this black hole-disk system produces a jet of high-energy particles. Shock waves within this jet are thought to produce a bright burst of X-rays and gamma rays observed to last only a few minutes. Interaction of the jet with the shell produces the X-ray afterglow, which can last for days or even months. The reason for the delay between the formation of the black hole and the production of the jet is not understood.

NASA's Marshall Space Flight Center in Huntsville, Ala., managed the Chandra program. (Image credit:
Illustration: CXC/M. Weiss
X-ray Image: NASA/CXC/MIT/N. Butler et al. )


Photo description: Chandra image of the supernova remnant DEM L71 Large 2254 x 1175 (300)
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Chandra image reveals supernova origin

NASA's Chandra X-ray Observatory image, left panel, of the supernova remnant DEM L71 reveals a hot inner cloud, aqua, of glowing iron and silicon surrounded by an outer blast wave. This outer blast wave is also visible at optical wavelengths, right panel. Data from the Chandra observation show that the central 10-million-degree Celsius cloud is the remains of a supernova explosion that destroyed a white dwarf star.

DEM L71 presents a textbook example of the double-shock structure expected to develop when a star explodes and ejects matter at high speeds into the surrounding interstellar gas. The expanding ejecta drive an outward-moving shock wave that races ahead of the ejecta into the interstellar gas, bright outer rim. The pressure behind this shock wave drives an inward-moving shock wave that heats the ejecta, seen as the aqua cloud.

The clear separation of the shocked matter and the heated ejecta in the Chandra image allowed astronomers to determine the mass and composition of the ejecta. The computed ejected mass was found to be comparable to the mass of the Sun. This and the X-ray spectrum, which exhibits a high concentration of iron atoms relative to oxygen and silicon, convincingly show that the ejecta are the remains of an exploded white dwarf star.

The size and temperature of the remnant indicate that it is several thousand years old.

Astronomers have identified two major types of supernovas: Type II, in which a massive star explodes; and Type Ia, in which a white dwarf star explodes because it has pulled too much material from a nearby companion star onto itself. If the mass of the white dwarf becomes greater than about 1.4 times the mass of the Sun, it becomes unstable and is blown apart in a thermonuclear explosion. This was the case in DEM L71.

One of the major goals of the study of supernova remnants is to determine the type of supernova explosion. The identification of DEM L71 as the remnant of an exploded white dwarf, or Type Ia supernova, represents a major step forward in understanding more about the ways in which stars explode.

The Marshall Center manages the Chandra program. (NASA/CXC/Rutgers/J. Hughes et al.)


Photo description: Composite image of the Black Widow Pulsar Large 2250 x 2250 (300)
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Cocoon found inside the Black Widow Pulsar

This composite Chandra X-ray Observatory image, in red and white, and optical, in green and blue, image reveals an elongated cloud, or cocoon, of high-energy particles flowing behind the rapidly rotating pulsar, B1957+20, the white point-like source. The pulsar, also known as the "Black Widow" pulsar, is moving through the galaxy at a speed of almost a million kilometers per hour. A bow shock due to this motion is visible to optical telescopes, shown in the green crescent shape. The pressure behind the bow shock creates a second shock wave that sweeps the cloud of high-energy particles back from the pulsar to form the cocoon.

The black widow pulsar is emitting intense high-energy radiation that appears to be destroying a companion star through evaporation. It is one of a class of extremely rapid rotating neutron stars called millisecond pulsars.

These objects are thought to be very old neutron stars that have been spun up to rapid rotation rates with millisecond periods by pulling material off their companions. The steady push of the infalling matter on the neutron star spins it up in much the same way as pushing on a merry-go-round causes it to rotate faster.

The advanced age, very rapid rotation rate, and relatively low magnetic field of millisecond pulsars put them in a separate class from young pulsars, such as the Crab Nebula. Yet the Chandra data show that this billion-year-old rejuvenated pulsar is an extremely efficient generator of matter and antimatter particles, just like its younger cousins.

The key is the rapid rotation of B1957+20. The NASA Chandra X-ray Observatory result confirms the theory that even a relatively weakly magnetized neutron star can generate intense electromagnetic forces and accelerate particles to high energies to create a pulsar wind, if it is rotating rapidly enough. (X-ray: NASA/CXC/ASTRON/B. Stappers et al.)


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Chandra X-ray Observatory Image of NGC 346: A Heart in the Darkness

This NASA Chandra X-ray Observatory image of the young star cluster NGC 346 highlights a heart-shaped cloud of 8 million degree Celsius gas in the central region. Evidence from radio, optical and ultraviolet telescopes suggests that the hot cloud, which is about 100 light years across, is the remnant of a supernova explosion that occurred thousands of years ago.

The progenitor could have been a companion of the massive young star that is responsible for the bright X-ray source at the top center of the image. This young star, HD 5980, one of the most massive known, has been observed to undergo dramatic eruptions during the last decade. An alternative model for the origin of the hot cloud is that eruptions of HD 5980 long ago produced the cloud of hot gas, in a manner similar to the gas cloud observed around the massive star Eta Carinae.

Future observations will be needed to decide between the alternatives. Until then, the nature of the heart in the darkness will remain mysterious. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA. (NASA/CXC/U.Liege/Y.Nazé et al.)


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X-rays reveal nature of spiral galaxy's boisterous activity

This Chandra X-ray Observatory image of M83 shows numerous point-like neutron star and black hole X-ray sources scattered throughout the disk of this spiral galaxy. The bright nuclear region of the galaxy glows prominently due to a burst of star formation that is estimated to have begun about 20 million years ago in the galaxy's time frame.

The observation revealed that the nuclear region contains a much higher concentration of neutron stars and black holes than the rest of the galaxy. Also discovered was a cloud of 7 million degree Celsius gas enveloping the nuclear region.

The picture that emerges is one of enhanced star formation in the nuclear region that has produced more massive stars, leading to more supernova explosions, neutron stars and black holes. This activity could also account for the hot gas cloud which shows evidence for an excess of carbon, neon, magnesium, silicon and sulfur atoms. Mass evaporating from massive stars, and the ejecta from supernovas have enriched the gas with carbon and other elements.

Hot gas with a slightly lower temperature of 4 million degrees was observed along the spiral arms of the galaxy. This suggests that star formation may be occurring at a more sedate rate in the spiral arms, consistent with the observation of proportionately fewer bright point-like sources there compared to the nucleus.

The Marshall Center manages the Chandra program. (NASA/CXC/UCL/R. Soria et al.)


Photo description: Chandra image of Sagittarius A*, the black hole at the Milky Way's center Large 2250 x 2250 (300)
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Chandra X-ray Observatory Image of Sagittarius A*

This Chandra X-ray Observatory image of the supermassive black hole at the Milky Way's center, a.k.a. Sagittarius A* or Sgr A*, was made from the longest X-ray exposure of that region to date. In addition to Sgr A* more than two thousand other X-ray sources were detected in the region, making this one of the richest fields ever observed.

During the two-week observation period, Sgr A* flared up in X-ray intensity half a dozen or more times. The cause of these outbursts is not understood, but the rapidity with which they rise and fall indicates that they are occurring near the event horizon, or point of no return, around the black hole. Even during the flares the intensity of the X-ray emission from the vicinity of the black hole is relatively weak. This suggests that Sgr A*, weighing in at 3 million times the mass of the Sun, is a starved black hole, possibly because explosive events in the past have cleared much of the gas from around it.

Evidence for such explosions was revealed in the image - huge lobes of 20 million-degree Centigrade gas (the red loops in the image at approximately the 2 o'clock and 7 o'clock positions) that extend over dozens of light years on either side of the black hole. They indicate that enormous explosions occurred several times over the last ten thousand years. Further analysis of the Sgr A* image is expected to give astronomers a much better understanding of how the supermassive black hole in the center of our galaxy grows and how it interacts with its environment. This knowledge will also help to understand the origin and evolution of even larger supermassive black holes found in the centers of other galaxies.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/CXC/MIT/F.K.Baganoff et al.)


Photo description: Chandra image of the star cluster RCW 38 Large 2242 x 2433 (300)
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Chandra image of the star cluster RCW 38

At a distance of 6,000 light years from Earth, the star cluster RCW 38 is a relatively close star-forming region. This image covers an area about five light years across, and contains thousands of hot, very young stars formed less than a million years ago. X-rays from the hot upper atmospheres of 190 of these stars were detected by NASA's Chandra X-ray Observatory.

In addition to the point-like emission from stars, the Chandra image revealed a diffuse cloud of X-rays enveloping the star cluster. The X-ray spectrum of the cloud shows an excess of high-energy X-rays, which indicates that the X-rays come from trillion-volt electrons moving in a magnetic field. Such particles are typically produced by exploding stars, or in the strong magnetic fields around neutron stars or black holes, none of which is evident in RCW 38.

One possible origin for the high-energy electrons is an undetected supernova that occurred in the cluster. Although direct evidence for such a supernova could have faded away thousands of years ago, a shock wave or a rapidly rotating neutron star produced by the outburst could be acting in concert with particles evaporating off the young stars to produce the high-energy electrons.

Regardless of the origin of the energetic electrons, their presence could change the chemistry of the disks that will eventually form planets around stars in the cluster. For example, in our own solar system, we find evidence of certain short-lived radioactive nuclei (Aluminum 26 being the most well known). This implies the existence of a high- energy process late in the evolution of our solar system. If our solar system was immersed for a time in a sea of energetic particles, this could explain the rare nuclides present in meteorites found on Earth today.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (/NASA/CXC/CfA/S. Wolk et al.)


Photo description: Chandra X-ray Observatory shows a cloud of hot gas speeding away from a black hole Large 2233 x 2133 (300)
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The most recent Chandra image of a binary star system known as SS 433 shows two high-speed lobes of 50-million-degree gas that are 3 trillion miles apart on opposite sides of a binary black hole system. As shown in the illustration (lower right), the binary system, which has a diameter several million times smaller than the distance between the lobes, consists of a massive star and a black hole with a disk of hot matter. Material is ejected from this disk in narrow jets that slowly wobble (represented by blue circular arrow), or precess, around a fixed axis (dotted white line).

The detection of the hot gas lobes so far away from the central black hole came as a surprise since earlier observations by Chandra and the Hubble Space Telescope had indicated that gas was cooling as it expanded away from the vicinity of the black hole in narrow jets. This led scientists to predict that no hot gas would be found farther than a few million kilometers from the black hole.

This observation implies that the gas in the jets has been reheated, most likely by collisions between blobs of gas. Long-term optical monitoring observations have shown that matter is ejected every few minutes from the vicinity of the black hole in bullet-like gaseous blobs. The blobs apparently travel outward at about a quarter of the speed of light for several months without colliding until a faster blob collides with a slower one, causing a pileup that reheats the gas.

SS 433 is similar to the XTE J1550-564 binary system, in that they both involve black holes that are producing high-speed jets of gas. However, there are significant differences. The X-ray emitting lobes in XTE J1550 are observed to be much farther from the black hole than those in SS 433, and the X-rays from the XTE J1550 lobes appear to be produced by a magnetized cloud of highly energetic electrons, not clouds of hot gas as in SS 433. These differences might be due to the mass of the companion stars, which are quite different. In XTE J1550, the companion star has a mass similar to that of the Sun, whereas in SS 433, the companion star's mass is estimated to be almost 20 times that of the Sun. Perhaps the rapid rate of evaporation of matter from the massive star could affect the behavior of the jets in SS 433.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (Credit: NASA/CXC/U. Amsterdam/S. Migliari et al.)


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The Chandra X-ray Observatory image of NGC 6240 — a butterfly-shaped galaxy that is the product of the collision of two smaller galaxies — revealed that the central region of the galaxy (inset) contains not one, but two active giant black holes.

Previous X-ray observatories had shown that the central region was an X-ray source, but astronomers did not know what was producing the X-rays. Radio, infrared, and optical observations had detected two bright nuclei, but their exact nature also remained a mystery.

Chandra was able to show that the X-rays were coming from the two nuclei, and determine their X-ray spectra. These cosmic fingerprints revealed features that are characteristic of supermassive black holes — an excess of high energy photons from gas swirling around a black hole, and X-rays from fluorescing iron atoms in gas near black holes.

Over the course of the next few hundred million years, the two supermassive black holes, which are about 3000 light years apart, will drift toward one another and merge to form one larger supermassive black hole. This detection of a binary black hole supports the idea that black holes grow to enormous masses in the centers of galaxies by merging with other black holes.

NGC 6240 is a prime example of a "starburst" galaxy in which stars are forming, evolving, and exploding at an exceptionally rapid rate due to a relatively recent merger (30 million years ago). Heat generated by this activity created the extensive multimillion degree Celsius gas seen in this image.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (Credit: NASA/CXC/MPE/S.Komossa et al.)


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Revealing Chandra image shows Mars glows in X-rays

This remarkable image from the Chandra X-ray Observatory image gave scientists their first look at X-rays from Mars.  In the sparse upper atmosphere of Mars, about 75 miles above its surface, the observed X-rays are produced by fluorescent radiation from oxygen atoms.

X-rays from the Sun impact oxygen atoms, knock electrons out of the inner parts of their electron clouds, and excite the atoms to a higher energy level in the process.  The atoms almost immediately return to their lower energy state and may emit a fluorescent X-ray in this process with an energy characteristic of the atom involved — oxygen in this case.  A similar process involving ultraviolet light produces the visible light from fluorescent lamps.

The X-ray power detected from the Martian atmosphere is very small, amounting to only 4 megawatts, comparable to the X-ray power of about ten thousand medical X-ray machines.  Chandra was scheduled to observe Mars when it was only 43.5 million miles from Earth, and also near the point in its orbit when it is closest to the Sun.

At the time of the Chandra observation, a huge dust storm developed on Mars that covered about one hemisphere, later to cover the entire planet. This hemisphere rotated out of view over the course of the 9-hour observation but no change was observed in the X-ray intensity, implying that the dust storm did not affect the upper atmosphere.

The astronomers also found evidence for a faint halo of X-rays that extends out to 4,350 miles above the surface of Mars.  Scientists believe the X-rays are produced by collisions of ions racing away from the Sun (the solar wind) with oxygen and hydrogen atoms in the tenuous exosphere of Mars.  NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (Credit: NASA/CXC/MPE/K.Dennerl et al.)


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Keith Hefner has been named program manager for NASA's Chandra X-ray Observatory at NASA's Marshall Space Flight Center in Huntsville, Ala. A native of Boaz, Ala., he will be responsible for planning, budgeting and operations for the world's most powerful X-ray telescope. Hefner joined Marshall in 1985. ( NASA/MSFC)


Photo description: Chandra's image of the NGC 720 galaxy enveloped in a cloud of hot gas challenges theories of gravity Large 2692 x 2692 (300)
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Chandra casts cloud on alternative to dark matter

An image from NASA's Chandra X-ray Observatory of galaxy NGC 720 shows the galaxy enveloped in a slightly flattened, or ellipsoidal cloud of hot gas that has an orientation different from that of the optical image of the galaxy. The flattening is too large to be explained by theories in which stars and gas are assumed to contain most of the mass in the galaxy.

According to the standard theory of gravity, the X-ray producing cloud would need an additional source of gravity - a halo of dark matter - to keep the hot gas from expanding away. The mass of dark matter required would be about five to 10 times the mass of the stars in the galaxy.

An alternative theory of gravity called MOND, for Modified Newtonian Dynamics, does away with the need for dark matter. However, MOND cannot explain the Chandra observation of NGC 720, which shows that the dark matter halo has a different shape from that of the stars and gas in the galaxy. This implies that dark matter is not just an illusion due to a shortcoming of the standard theory of gravity - it is real.

The Chandra data also fit predictions of a cold dark matter model. According to this model, dark matter consists of slowly moving particles, which interact with each other and "normal" matter only through gravity. Other dark matter models, such as self-interacting dark matter, and cold molecular dark matter, are not consistent with the observation in that they require a dark matter halo that is too round or too flat, respectively.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. ( NASA/CXC/UCI/D.Buote et al.)


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Chandra tracks evolution of X-ray jets

A series of Chandra images has allowed scientists to trace the evolution of large-scale X-ray jets produced by a black hole in a binary star system. As the schematic shows, gaseous matter pulled from a normal star forms a disk around the black hole. The gas is heated to temperatures of millions of degrees, and intense electromagnetic forces in the disk can expel jets of high-energy particles.

An outburst of X-rays from the source, XTE J1550-564, was detected by NASA's Rossi X-ray Timing Explorer (RXTE) in 1998. Further observations with Chandra and radio telescopes detected first one jet (left), then another opposing jet (right) of high-energy particles moving away from the black hole at about half the speed of light. Four years after the outburst, the jets had moved more than three light years apart with the left jet slowing down and disappearing.

The observations indicate that the jet on the left is moving along a line tilted toward Earth, whereas the jet on the right is tilted away from Earth. This alignment explains why the left jet appears to have traveled farther from the black hole than the jet on the right, and why the left jet faded first.

However, with this alignment, the relative brightness of the right jet is difficult to understand because it is receding, and should be dimmer than it appears. One explanation is that it is plowing into a dense cloud of gas. The resistance of the gas would slow down the jet, and produce a shock wave that could energize the electrons in the jet, causing it to brighten. The observed cometary shape of the right jet indicates that it is in fact interacting with interstellar gas.

The ejection of jets from stellar black holes and supermassive black holes is a common occurrence in the universe, and appears to be one of the primary ways that black holes inject energy into their environment. Although all jets are assumed to decelerate because of the resistance of the gas through which they move, the process can take millions of years for jets from supermassive black holes.

The XTE J1550 jets are the first ones caught in the act of slowing down. During the past four years astronomers have observed a process that would take as much as a million years to unfold for a supermassive black hole jet. This underscores the enormous value of studying black holes in our galaxy such as XTE J1550.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (Photo credit: X-ray (NASA/CXC); Illustration credit: (CXC/M.Weiss))


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Crab Nebula: Space movie reveals shocking secrets of the Crab pulsar

The Chandra images in this collage were made over a span of several months (ordered left to right, except for the close-up). They provide a stunning view of the activity in the inner region around the Crab Nebula pulsar, a rapidly rotating neutron star seen as a bright white dot near the center of the images.

A wisp can be seen moving outward at half the speed of light from the upper right of the inner ring around the pulsar. The wisp appears to merge with a larger outer ring that is visible in both X-ray and optical images.

The inner X-ray ring consists of about two-dozen knots that form, brighten and fade. As a high-speed wind of matter and antimatter particles from the pulsar plows into the surrounding nebula, it creates a shock wave and forms the inner ring. Energetic shocked particles move outward to brighten the outer ring and produce an extended X-ray glow.

Enormous electrical voltages generated by the rotating, highly magnetized neutron star accelerate particles outward along its equator to produce the pulsar wind. These pulsar voltages also produce the polar jets seen spewing X-ray emitting matter and antimatter particles perpendicular to the rings.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/CXC/ASU/J. Hester et al.)


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Abell 2104: Chandra Reveals Black Hole Activity in Old Galaxies

A Chandra observation of the galaxy cluster A2104 revealed six bright X-ray sources that are associated with supermassive black holes in red galaxies in the cluster. Since red galaxies are thought to be composed primarily older stars, and to contain little gas, the observation came as a surprise to astronomers.

Powerful X-ray emission from a supermassive black hole comes from gas heated as it falls toward the black hole, so an abundant supply of gas is needed to produce the bright X-ray sources detected by Chandra.

It is generally believed that as galaxies move through the hot cluster gas at high speeds, they are stripped of their interstellar gas, much as a strong wind strips leaves from a tree. Galaxies can also lose gas through collisions with other galaxies in the cluster. The presence of these six X-ray sources indicates that these supermassive black holes have somehow retained a fuel source, despite the harsh environment of the clusters.

It could be that galaxies are better at holding onto a supply of gas and dust than previously thought, particularly deep down at their cores near the supermassive black hole. Such gas and dust may explain why the centers of the galaxies are obscured at optical wavelengths.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/CXC/Carnegie Observatories/P. Martini et al.)


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Chandra X-ray Observatory image of Tycho's Supernova Remnant

This Chandra image reveals fascinating details of the turbulent debris created by a supernova explosion observed by the Danish astronomer Tycho Brahe in 1572. The colors show different X-ray energies, with red, green, and blue representing low, medium and high energies, respectively. The image is cut off at the bottom because the southernmost region of the remnant fell outside the field of view of the detector.

A shock wave produced by the expanding debris is outlined by the strikingly sharp blue circular arcs of twenty million degree Celsius gas seen on the outer rim. The stellar debris, which has a temperature of about ten million degrees and is visible only in X-rays, shows up as mottled yellow, green and red fingers of gas.

Tycho's supernova remnant presents several interesting contrasts with the Cassiopeia A (Cas A) supernova remnant. The debris for Tycho is distributed in clumps rather than knots as in Cas A, and its outer shock wave can be seen in smooth and continuous arcs rather than being fragmented, as in Cas A.

Also, no central point source is detected in Tycho, in contrast to Cas A. The absence of a central point source is consistent with other evidence that Tycho is a Type Ia supernova, which is thought to signal the detonation and destruction of a white dwarf star. Theory predicts that a white dwarf star will explode when infalling matter from a companion star increases the mass of the white dwarf beyond a critical mass limit, known as the Chandrasekhar limit.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/CXC)


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Chandra's composite image of the Centaurus A galaxy

A composite X-ray (blue), radio (pink and green), and optical (orange and yellow) image of the galaxy Centaurus A presents a stunning tableau of a galaxy in turmoil. A broad band of dust and cold gas is bisected at an angle by opposing jets of high-energy particles blasting away from the supermassive black hole in the nucleus. Two large arcs of X-ray emitting hot gas were discovered in the outskirts of the galaxy on a plane perpendicular to the jets.

The arcs of multimillion-degree gas appear to be part of a projected ring 25,000 light years in diameter. The size and location of the ring indicates that it may have been produced in a titanic explosion that occurred about ten million years ago.

Such an explosion would have produced the high-energy jets, and a galaxy-sized shock wave moving outward at speeds of a million miles per hour. The age of 10 million years for the outburst is consistent with optical and infrared observations that indicate that the rate of star formation in the galaxy increased dramatically at about that time.

Scientists have suggested that all this activity may have begun with the merger of a small spiral galaxy and Centaurus A about 100 million years ago. Such a merger could eventually trigger both the burst of star formation and the violent activity in the nucleus of the galaxy. The tremendous energy released when a galaxy becomes "active" can have a profound influence on the subsequent evolution of the galaxy and its neighbors. The mass of the central black hole can increase, the gas reservoir for the next generation of stars can be expelled, and the space between the galaxies can be enriched with heavier elements.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program.

Image Credits:
X-ray: NASA/CXC/SAO/M. Karovska et al.
Optical: Digital Sky Survey/U.K. Schmidt Image/STScI
21-cm Radio: NRAO/VLA/Schiminovich et al.
Contiuum Radio: NRAO/VLA/J. Condon et al.


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Chandra image of the dwarf galaxy NGC 1569

The Chandra image of NGC 1569, a dwarf galaxy 7 million light years from Earth, shows large hot bubbles, or lobes extending above and below a disk of gas along the equator of the galaxy. The 27-hour observation allowed scientists to measure for the first time the concentration of oxygen, neon, magnesium, and silicon in the bubbles and the disk. They found that bubbles contain oxygen equal to the oxygen contained in 3 million suns.

For the last 10 million to 20 million years NGC 1569 has been undergoing a burst of star formation and supernova explosions, perhaps triggered by a collision with a massive gas cloud. The supernovas eject oxygen and other heavy elements at high velocity into the gas in the galaxy, heating it to millions of degrees. Hot gas boils off the gaseous disk of the galaxy to form the bubbles, which expand out of the galaxy at speeds of hundreds of thousands of miles per hour.

Dwarf galaxies are much smaller than ordinary galaxies like our Milky Way. Because of their size, they have relatively low gravity and matter can escape from them more easily. This property, combined with the fact that dwarf galaxies are the most common type of galaxy in the universe, makes them very important in understanding how the universe was seeded with various elements billions of years ago, when galaxies were forming. (Credit: NASA/CXC/UCSB/C. Martin et al.)


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High-energy activity heats up the whirlpool

X-rays from a rare type of supernova in the Whirlpool Galaxy were recently observed, thanks to the fine resolution of NASA's Chandra X-ray Observatory. The team of researchers also detected a large number of point-like X-ray sources due to black holes and neutron stars in binary star systems.

Chandra's image highlights the energetic central regions of the two interacting galaxies, NGC 5194 (center) and its smaller companion (upper left) NGC 5195, that are collectively called the Whirlpool Galaxy.

The inset contains an expanded image of the central region of NGC 5194. Extending to the north and south of the bright nucleus are clouds of multimillion-degree gas, with diameters of about 1500 light years and 500 light years, respectively. The similarity of these features with ones observed at radio wavelengths suggests that the gas is heated by high-velocity jets produced near a supermassive black hole in the nucleus of the galaxy.

On the lower left of the inset image is a faint source identified with a supernova discovered in 1994 by amateur astronomers in Georgia, and subsequently determined to be an unusual Type Ic supernova. The massive stars responsible for these supernovas are thought to have lost their outer layers of hydrogen and helium gas thousands of years before the explosion, either through evaporation or transfer to a companion.

In the millennia before a doomed star explodes into a supernova, it loses mass. X-ray observations of the supernova shock wave provide a method to sensitively probe into this process. The Chandra data from SN 1994I and its surrounding area indicate that the progenitor star evaporated material into a cloud around the star that has a diameter at
least 0.2 light years. Further monitoring over the years will tell just how large the cloud is, and how long the star was losing mass before it exploded.

Andrew Wilson of the University of Maryland, in College Park, was the principal investigator for the Chandra observations of M51. Other scientists involved in the research were Yuichi Terashima of the University of Maryland, and Stefan Immler of the University of Massachusetts, Amherst.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (Credit: NASA/CXC/UMD/A. Wilson et al.)




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SNR G54.1+0.3: Energetic ring narks spot that leads to discovery of neutron star

The Chandra image of the distant supernova Remnant SNR G54.1+0.3 reveals a bright ring of high-energy particles with a central point-like source. This observation enabled scientists to use the giant Arecibo Radio Telescope to search for and locate the pulsar, or neutron star that powers the ring. The ring of particles and two jet-like structures appear to be due to the energetic flow of radiation and particles from the rapidly spinning neutron star.

During the supernova event, the core of a massive star collapsed to form a neutron star that is highly magnetized and creates an enormous electric field as it rotates. The electric field accelerates particles near the neutron star and produces jets blasting away from the poles, and as a disk of matter and anti-matter flowing away from the equator at high speeds. As the equatorial flow rams into the particles and magnetic fields in the nebula, a shock wave forms. The shock wave boosts the particles to extremely high energies causing them to glow in X-rays and produce a bright ring. The particles stream outward from the ring and the jets to supply the extended nebula, which spans approximately 6 light years.

The features observed in SNR G54.1 are very similar to other "pulsar wind nebulas" found by Chandra in the Crab Nebula, the Vela supernova remnant, and PSR 1509-58. By analyzing the similarities and differences between these objects, scientists hope to better understand the fascinating process of transforming the rotational energy of the neutron star into high-energy particles with very little frictional heat loss.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (Credit: NASA/CXC/UMass/F. Lu et al.)


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Artist's concept of the neutron star 1E 1207.4-5209.

This artist's conception illustrates 1E 1207.4-5209, a neutron star with a polar hot spot and a strong magnetic field (purple lines). The neutron star is about 7,000 light years from Earth.

The graph in the box to the right of the star shows the expected (dashed blue line) and the observed (solid green line) spectra of the X-radiation from the hot spot. The dips in the observed spectrum are absorption features due to gas in the atmosphere of the neutron star.

According to the team of scientists that made the Chandra observation of 1E 1207, the most likely explanation for the dips in the spectrum is absorption by helium ions in a magnetic field about a hundred trillion times more intense than the Earth's magnetic field. This interpretation implies that the strong gravity of the neutron star has reduced the energy of the photons by 17 percent. The reduction of photon energy, known as the gravitational redshift, enables astronomers to relate the mass to the radius of the star. This information can then be used to help determine whether the collapsed star is composed mostly of neutrons, or contains large amounts of sub-nuclear particles called pions, kaons, or free quarks.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (CXC/M.Weiss)


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Chandra image of the elliptical galaxy NGC 4697

Chandra's image of the elliptical galaxy NGC 4697 reveals diffuse hot gas dotted with many point-like sources. As in the elliptical galaxies, NGC 4649 and NGC 1553, the point-like sources are due to black holes and neutron stars in binary star systems. Material pulled off a normal star is heated and emits X-radiation as it falls toward its black hole or neutron star companion.

Black holes and neutron stars are the end state of the brightest and most massive stars. Chandra's detection of numerous neutron stars and black holes in this and other elliptical galaxies shows that these galaxies once contained many very bright, massive stars, in marked contrast to the present population of low-mass faint stars that now dominate elliptical galaxies.

An unusually large number of the binary star X-ray sources in NGC 4697 are in "globular star clusters," round balls of stars in the galaxy that contain about one million stars in a volume where typically only one would be found. This suggests that the extraordinarily dense environment of globular clusters may be a good place for black holes or neutron stars to capture a companion star.

The origin of the hot gas cloud enveloping the galaxy is not known. One possibility is that the gas lost by evaporation from normal stars- so-called stellar winds - is heated by these winds and by supernova explosions.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program.

(NASA/CXC/UVa/C.Sarazin et al.)

 

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Chandra X-ray Observatory image of the NGC 1553 Galaxy

Chandra's image of the lenticular -- an elliptical-type galaxy with a disk of old stars -- galaxy NGC 1553 reveals diffuse hot gas dotted with many point-like sources. As in the elliptical galaxies, NGC 4649 and NGC 4697, the point-like sources are due to black holes and neutron stars in binary star systems where material pulled off a normal star is heated and emits X-radiation as it falls toward its black hole or neutron star companion.

Black holes and neutron stars are the end state of the brightest and most massive stars. Chandra's detection of numerous neutron stars and black holes in this and other elliptical galaxies shows that these galaxies once contained many very bright, massive stars, in marked contrast to the present population of low-mass faint stars that now dominate elliptical galaxies.

The bright central source in NGC 1553 is probably due to a supermassive black hole in the nucleus of the galaxy. The nature of the spiral feature curling out from either side of this source is not known. It could be caused by shock waves from a pair of bubbles of high energy particles that were ejected from the vicinity of the supermassive black hole.

(NASA/CXC/UVa/E.Blanton et al.)

 

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Chandra X-ray Observatory image of the elliptical galaxy NGC 4649

Chandra's image of the elliptical galaxy NGC 4649 reveals a large, bright cloud of hot gas and 165 point-like sources. As in the elliptical galaxies, NGC 4697 and NGC 1553, most of the point-like sources are due to black holes and neutron stars in binary star systems.

Black holes and neutron stars are the end state of the brightest and most massive stars. Chandra's detection of numerous neutron stars and black holes in this and other elliptical galaxies shows that these galaxies once contained many very bright, massive stars, in marked contrast to the present population of low-mass faint stars that now dominate elliptical galaxies.

Many of the X-ray binaries are in "globular star clusters," round balls of stars that contain about one million stars in a volume where typically only one would be found. This suggests that the extraordinarily dense environment of globular clusters may be a good place for black holes or neutron stars to capture a companion star.

The hot gas cloud filling the galaxy has a temperature of about 10 million degrees Celsius. In the bright central region there appear to be bright fingers of X-ray emission which could be due to rising cells of hot gas.

(NASA/CXC/UVa/S.Randall et al.)


Chandra's orbit was selected by, from left, Russell Stone, Steve Evans and Larry Mullins. Large 1500 x 978 (300)
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Every 64 hours, NASA's Chandra X-ray Observatory follows a path that dodges darkness, stretches one-third of the way to the Moon, and has a more elliptical shape than most orbiting satellites. Chandra's unique orbit was selected by, from left, Russell Stone, Steve Evans and Larry Mullins, all of NASA's Marshall Space Flight Center in Huntsville, Ala. (NASA/MSFC/Emmett Given)


Photo description: This "true color" Chandra image of N132D shows the beautiful, complex remnant of an explosion of a massive star in the Large Magellanic Cloud, a nearby galaxy about 180,000 light years from Earth Large 2263 x 2263 (300)
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N132D: Glowing Remnant from a Star-Shattering Explosion

This "true color" Chandra image of N132D shows the beautiful, complex remnant of an explosion of a massive star in the Large Magellanic Cloud, a nearby galaxy about 180,000 light years from Earth. The colors represent different ranges of X-rays, with red, green, and blue representing, low, medium, and higher X-ray energies respectively. Supernova remnants comprise debris of a stellar explosion and any matter in the vicinity that is affected by the expanding debris. In the case of N132D, the horseshoe shape of the remnant is thought to be due to shock waves from the collision of the supernova ejecta with cool giant gas clouds. As the shock waves move through the gas they heat it to millions of degrees, producing the glowing X-ray shell. NASA's Marshall Space Flight Center in Huntsville, ala., manages the Chandra program for NASA.

Credit: NASA/SAO/CXC


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Chandra X-ray Observatory image of Arp 270: Merging galaxies and cosmic collisions

The Chandra image of Arp 270 shows two galaxies about 90 million light years from Earth in the early stage of a merger. The future evolution of these galaxies will be radically changed by the merger as their mutual gravity distorts their shape, and the collision of gas clouds in the galaxies stimulates the formation of new stars.

The hot spots (blue) located where the disks of the galaxies are colliding are thought to be due to the formation of hundreds of thousands of new stars as the two gaseous disks rotate through each other.

These bursts of star formation create many massive stars that generate intense winds of hot gas, and these stars eventually explode as supernovas. This violent activity produces the hot gas clouds that surround the galaxy disks (red).

Astronomers hope to understand more about how supermassive black holes are formed in the centers of galaxies by studying galaxies at different stages in the merging process. These studies will also provide valuable insight as to how our own Milky Way Galaxy formed and evolved.

In the image, red represents low, green intermediate, and blue high energy (temperature) X-rays.

The Marshall Center manages the Chandra program.

(NASA/U. Birmingham/A.Read)


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Chandra X-ray Observatory image of the Tarantula Nebula

The Chandra image of the Tarantula Nebula gives scientists a close-up view of the drama of star formation and evolution. The Tarantula, also known as 30 Doradus, is in one of the most active star-forming regions in our local group of galaxies. Massive stars are producing intense radiation and searing winds of multimillion-degree gas that carve out gigantic super-bubbles in the surrounding gas. Other massive stars have raced through their evolution and exploded catastrophically as supernovas, leaving behind pulsars and expanding remnants that trigger the collapse of giant clouds of dust and gas to form new generations of stars.

30 Doradus is located about 160,000 light years from Earth in the Large Magellanic Cloud, a satellite galaxy of our Milky Way Galaxy. It allows astronomers to study the details of starbursts - episodes of extremely prolific star formation that play an important role in the evolution of galaxies.

At least 11 extremely massive stars with ages of about 2 million years are detected in the bright star cluster in the center of the image. This crowded region contains many more stars whose X-ray emission is unresolved. The brightest source in this region known as Melnick 34, a 130 solar-mass star located slightly to the lower right of center. On the lower right of this panel is the supernova remnant N157B, with its central pulsar.

In the image, lower energy X-rays appear red, medium energy green and high energy are blue.

The Marshall Center manages the Chandra program. (NASA/CXC/Penn State/L. Townsley et al.)


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Chandra image of the galaxy Arp 220

The Chandra observations of the peculiar galaxy Arp 220 gives new insight into what happens when two galaxies the size of the Milky Way collide. The image shows a bright central region at the waist of a glowing hour-glass-shaped cloud of multimillion degree gas that is rushing out of the galaxy at hundreds of thousands of miles per hour. This "superwind" is thought to be due to explosive activity generated by the formation of hundreds of millions of new stars.

Further out, spanning a distance of 75,000 light years, are giant lobes of hot gas. These could be galactic remnants that have been flung into intergalactic space by the early impact of the collision. Whether the lobes will continue to expand into space or fall back into Arp 220 is unknown.

In the central region of Arp 220, the Chandra observations allowed astronomers to pinpoint an X-ray source at the exact location of the nucleus of one of the pre-merger galaxies. Another fainter X-ray source nearby may coincide with the nucleus of the other galaxy remnant. These sources could be due to supermassive black holes at the centers of the merging galaxies. In a few hundred million years the two supermassive black holes could merge to produce a larger, supermassive black hole in the center of the conglomerate galaxy.

Arp 220, at a relatively nearby distance of about 250 million light years from Earth, is a prototype for understanding what conditions were like in the early universe when massive galaxies and supermassive black holes may have been formed by numerous galaxy collisions.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/SAO/CXC/J. McDowell et al.)


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3C58: Cosmic X-rays May Reveal New Form of Matter

Chandra observations of RXJ1856.5-3754 and the pulsar in 3C58 suggest that the matter in these collapsed stars is even denser than nuclear matter, the most dense matter found on Earth. This raises the possibility that these stars are composed of free quarks or crystals of sub-nuclear particles, rather than neutrons.

By combining Chandra and Hubble Space Telescope data, astronomers found that RXJ1856 radiates like a solid body with a temperature of 700,000 degrees Celsius and has a diameter of about 7 miles.

This size is too small to reconcile with the standard models of neutron stars. One exciting possibility, predicted by some theories, is that the neutrons in the star have dissolved at very high density into a soup of "up," "down" and "strange" quarks to form a "strange quark star," which would explain the smaller radius.

Observations of 3C58, the remnant of a supernova noted on Earth in AD 1181, reveal that the pulsar in the core has a temperature much lower than expected. This suggests that an exotic, denser state of matter might exist inside this star as well.

These observations demonstrate that the universe can be used as a laboratory to explore physics under conditions that are not accessible on Earth.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/SAO/CXC/P.Slane et al.)

 

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RXJ1856.5-3754: Cosmic X-rays May Reveal New Form of Matter

Chandra observations of RXJ1856.5-3754 and the pulsar in 3C58 suggest that the matter in these collapsed stars is even denser than nuclear matter, the most dense matter found on Earth. This raises the possibility that these stars are composed of free quarks or crystals of sub-nuclear particles, rather than neutrons.

By combining Chandra and Hubble Space Telescope data, astronomers found that RXJ1856 radiates like a solid body with a temperature of 700,000 degrees Celsius and has a diameter of about 7 miles.

This size is too small to reconcile with the standard models of neutron stars. One exciting possibility, predicted by some theories, is that the neutrons in the star have dissolved at very high density into a soup of "up," "down" and "strange" quarks to form a "strange quark star," which would explain the smaller radius.

Observations of 3C58, the remnant of a supernova noted on Earth in AD 1181, reveal that the pulsar in the core has a temperature much lower than expected. This suggests that an exotic, denser state of matter might exist inside this star as well.

These observations demonstrate that the universe can be used as a laboratory to explore physics under conditions that are not accessible on Earth.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/SAO/CXC/J. Drake et al.)


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Gas clouds strike a delicate balance: Chandra X-ray Observatory image of the Coma Cluster

This Chandra image shows the central region — about 1.5 million light years across - of the Coma Cluster. The cluster contains thousands of galaxies enveloped by a vast 100 million-degree Celsius gas cloud.

Of particular interest are the concentrations of cooler (10 to 20 million-degrees) gas around the large galaxies NGC 4874 (left), and NGC 4889 (right). These clumps of gas, which are 10,000 light years in diameter, are thought to be produced by matter ejected from stars in the galaxies over a period of about a billion years.

As discussed by Alexey Vikhlinin and his colleagues at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, in the 2001 July 10 issue of The Astrophysical Journal, the observation of relatively cool gas clouds in two large galaxies indicates that they are unlikely to be short-lived features. The scientists suggest that the clouds exist in a delicate balance in which the energy lost by X-radiation is precisely balanced by energy gained by heat conduction from the hot gas of the cluster.

Because of the large difference in temperature between the hot gas and the cool clouds — like a snowball in a blast furnace — this balance would require that the heat flow from the hot gas be greatly reduced, perhaps by the magnetic fields in the galaxies that separate the hot and cold components.

The Marshall Center manages the Chandra program. (NASA/CXC/SAO/A. Vikhlinin et al.)


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Chandra image of three most distant quasars

These three quasars, recently discovered at optical wavelengths by the Sloan Digital Sky Survey, are 13 billion light years from Earth, making them the most distant known quasars. The X-rays Chandra detected were emitted when the universe was only a billion years old, about 7 percent of the present age of the universe.

A surprising result was that the power output and other properties of these quasars are similar to less distant quasars. This indicates that the conditions around these quasars' central supermassive black holes must also be similar, contrary to some theoretical expectations. As astronomer Smita Mathur of Ohio State, who was involved in the research said, "Perhaps the most remarkable thing about them is that they are so absolutely unremarkable."

By various estimates, the supermassive black holes in these quasars weighed in at somewhere between one and 10 billion times the mass of the Sun. The implication is that the black holes put on a lot of weight soon after the galaxies formed. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. (NASA/CXC/PSU/N. Brandt et al.)


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Chandra X-ray Observatory image of the twin quasar Q2345+007

The Chandra image of the twin quasar Q2345+007 A, B shows that they are not identical twins. This means that it is unlikely that they are an optical illusion, rather, they were probably created by merging galaxies.

When galaxies collide, the flow of gas onto the central supermassive black holes of each of the galaxies can be enhanced, resulting in two quasars. The light from the quasar pair started its journey toward Earth 11 billion years ago. Galaxies were about three times closer together then than they are now, so collisions were much more likely.

Quasar pairs that are seen close to one another on the sky and are at the same distance from Earth often turn out to be an illusion as part of a gravitationally lensed system. In these cases, the image of a single quasar has been split into two or more images as its light has been bent and focused on its way to Earth by the gravity of an intervening massive object like a galaxy, or a cluster of galaxies.

The quasar pair Q2345+007 A, B was thought to be such an illusion because of the remarkably similar patterns of the light, or spectra, from the pair at both optical and ultraviolet wavelengths. However no intervening galaxy or cluster has been found for this pair, leading to the speculation that the gravitational light-bending might be caused by a new type of cluster that contains hot gas and dark matter, but no stars. Such a "dark cluster" would be invisible to optical and ultraviolet telescopes, but would be detectable in X-rays.

The Chandra X-ray images showed no evidence for a massive dark cluster. Further, the X-ray spectra of the two quasars were distinctly different, supporting the idea that they are distinct objects, rather than a mirage.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA. (NASA/SAO/CXC/P.Green et al.)


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Chandra X-ray Observatory image of Jupiter

This image of Jupiter shows concentrations of auroral X-rays near the north and south magnetic poles. While Chandra observed Jupiter for its entire 10-hour rotation, the northern auroral X-rays were discovered to be due to a single `hot spot' that pulsates with a period of 45 minutes, similar to high-latitude radio pulsations previously detected by NASA's Galileo and Cassini spacecraft.

Although there had been prior detections of X-rays from Jupiter with other X-ray telescopes, no one expected that the sources of the X-rays would be located so near the poles. The X-rays are thought to be produced by energetic oxygen and sulfur ions that are trapped in Jupiter's magnetic field and crash into its atmosphere. Before Chandra's observations, the favored theory held that the ions were mostly coming from regions close to the orbit of Jupiter's moon, Io.

Chandra's ability to pinpoint the source of the X-rays has cast serious doubt on this model. Ions coming from near Io's orbit cannot reach the observed high latitudes. The energetic ions responsible for the X-rays must come from much further away than previously believed.

One possibility is that particles flowing out from the sun are captured in the outer regions of Jupiter's magnetic field, then accelerated and directed toward its magnetic pole. Once captured, the ions would bounce back and forth in the magnetic field, from Jupiter's north pole to south pole in an oscillating motion that could explain the pulsations. (NASA/CXC/SWRI/G.R. Gladstone et al.)


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Chandra reveals bow-shaped shock wave in galaxy cluster

Chandra's image of the extremely hot galaxy cluster 1E0657-56 reveals a bow-shaped shock wave toward the right side of the cluster. This feature, thought to be the result of the merger of a smaller group or sub-cluster of galaxies with 1E0657-56, gives astronomers a rare opportunity to study how clusters grow.

The shock wave appears to have been formed as 70 million degree Celsius gas in the sub-cluster plowed through 100 million degree gas in the main cluster at a speed of about 6 million miles per hour. This motion created a wind that stripped the cooler gas from the sub-cluster, similar to leaves from a tree being blown off in a storm.

The speed, appearance and shape of the sub-cluster indicates that it would have passed through the core of the larger cluster about 150 million years ago. By the time the gravity of the cluster stops the motion of the sub-cluster, it is likely that the cooler gas will have been totally stripped.

1E0657-56 is of great interest because it is one of the hottest known clusters. Astronomers hope to use this and future observations to determine if the high temperature of the cluster gas is due to shocks waves produced by the merger of many sub-clusters. (NASA/CXC/SAO/M. Markevitch et al.)


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Chandra X-ray Observatory scores a double bonus with a distant quasar

The X-ray image of the quasar PKS 1127-145, a highly luminous source of X-rays and visible light about 10 billion light years from Earth, shows an enormous X-ray jet that extends at least a million light years from the quasar. The jet is likely due to the collision of a beam of high-energy electrons with microwave photons.

The high-energy beam is thought to have been produced by explosive activity related to gas swirling around a supermassive black hole. The length of the jet and the observed bright knots of X-ray emission suggest that the explosive activity is long-lived but intermittent.

On their way to Earth, the X-rays from the quasar pass through a galaxy located 4 billion light years away. Atoms of various elements in this galaxy absorb some of the X-rays, and produce a dimming of the quasar's X-rays, or an X-ray shadow. In a similar way, when our body is X-rayed, our bones produce an X-ray shadow. By measuring the amount of absorption astronomers were able to estimate that 4 billion years ago, the gas in the absorbing galaxy contained a much lower concentration of oxygen relative to hydrogen gas than does our galaxy - about five times lower. These observations will give astronomers insight into how the oxygen supply of galaxies is built up over the eons.

The Marshall Center manages the Chandra program. (NASA/CXC/A. Siemiginowska (CfA) & J. Bechtold (U. Arizona))


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Chandra image of the Centaurus galaxy

The Chandra image of the Centaurus galaxy cluster shows a long plume-like feature resembling a twisted sheet. The plume is some 70,000 light years in length and has a temperature of about 10 million degrees Celsius. It is several million degrees cooler than the hot gas around it, as seen in this temperature-coded image in which the sequence red, yellow, green, blue indicates increasing gas temperatures.

The plume contains a mass comparable to 1 billion suns. It may have formed by gas cooling from the cluster onto the moving target of the central galaxy, as seen by Chandra in the Abell 1795 cluster. Other possibilities are that the plume consists of debris stripped from a galaxy that fell into the cluster, or that it is gas pushed out of the center of the cluster by explosive activity in the central galaxy. A problem with these ideas is that the plume has the same concentration of heavy elements such as oxygen, silicon, and iron as the surrounding hot gas. (NASA/IOTA/J. Sanders and A. Fabian)


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X-ray mosaic of galactic center

This 400 by 900 light-year mosaic of several Chandra images of the central region of our Milky Way galaxy reveals hundreds of white dwarf stars, neutron stars, and black holes bathed in an incandescent fog of multimillion-degree gas. The supermassive black hole at the center of the galaxy is located inside the bright white patch in the center of the image. The colors indicate X-ray energy bands - red (low), green (medium), and blue (high). (NASA/UMass/D. Wang et al.)


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Chandra Image of Abell 2597

This X-ray image of the galaxy cluster Abell 2597, taken by NASA's Chandra X-ray Observatory, shows a vast bright cloud of hot gas with two cavities on the upper left and lower right, about 100,000 light years from the center of the cluster. These so-called ghost cavities are thought to be 100-million-year old relics of an ancient eruption that originated around a supermassive black hole in the core of a centrally located galaxy. (NASA/CXC/Ohio U./B. McNamara et al. photo)


Chandra image of the NGC 4636 galaxy

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Chandra's images of the elliptical NGC 4636 show spectacular symmetric arms, or arcs, of hot gas extending 25,000 light years into a huge cloud of multimillion-degree-Celsius gas that envelopes the galaxy. At a temperature of 10 million degrees, the arms are 30 percent hotter than the surrounding gas cloud.

The temperature jump, together with the symmetry and scale of the arms indicate that the arms are the leading edge of a galaxy-sized shock wave that is racing outward from the center of the galaxy at 435 miles (700 kilometers) per second. An explosion with an energy equivalent to several hundred thousand supernovas would be required to produce this effect.

This eruption could be the latest episode in a feedback cycle of violence that keeps the galaxy in a state of turmoil. The cycle starts when a hot gas cloud that envelops the stars in the galaxy cools and falls inward toward a central, massive black hole. The feeding of the black hole by the infalling gas leads to an explosion that heats the hot gaseous envelope, which then cools over a period of several million year to begin the cycle anew.

Credit: NASA/CXC/SAO/C. Jones et al.

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Chandra image of Venus

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Chandra image of Venus

This Chandra image, the first X-ray image ever made of Venus, shows a half crescent due to the relative orientation of the sun, Earth and Venus. The X-rays from Venus are produced by fluorescent radiation from oxygen and other atoms in the atmosphere between 120 and 140 kilometers above the surface of the planet. In contrast, optical light from Venus is caused by the reflection from clouds 50 to 70 kilometers above the surface. Solar X-rays bombard the atmosphere of Venus, knock electrons out of the inner parts of atoms, and excite the atoms to a higher energy level. The atoms almost immediately return to their lower energy state with the emission of a fluorescent X-ray. A similar process involving ultraviolet light produces the visible light from fluorescent lamps. This and future X-ray images will enable scientists to examine regions of the Venusian atmosphere that are difficult to investigate otherwise.

Credit: NASA/MPE/K.Dennerl et al.

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Illustration of the binary system 44i Bootis

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Illustration of the binary system 44i Bootis

This artist's conception depicts the two closely orbiting stars of 44i Bootis. These two stars circle around each other at a rapid rate, passing in front of one another every three hours. The red arrow in the illustration indicates the direction that the stars are orbiting. The plots to the right show Chandra data on X-ray emission from Neon ions. The four panels show the shift in wavelength at which the Neon X-ray emission peaks as the stars orbit one another. By using the Doppler effect-the same process that causes the wavelength of an ambulance's siren to shift down and up as the ambulance approaches and recedes-astronomers were able to pinpoint the location of the source of most of the X-rays. They found to their surprise that the large white spot on the larger star produces at least half of the X-rays from this system. In contrast, the X-ray active regions on our Sun tend to be near the equator.

PHOTO: CXC/M.Weiss

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Chandra image of G292.0+1.8 supernova

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Chandra looks at the aftermath of a massive star explosion

NASA’s Chandra X-ray Observatory has captured a spectacular image of G292.0+1.8, a young, oxygen-rich supernova remnant with a pulsar at its center surrounded by outflowing material.  Astronomers know that pulsars are formed in supernova explosions, but they are currently unable to identify what types of massive stars must die in order for a pulsar to be born.  Now that Chandra has revealed strong evidence for a pulsar in G292.0+1.8, astronomers can use the pattern of elements seen in the remnant to make a much closer connection between pulsars and the massive stars from which they form.

This Chandra image shows a rapidly expanding shell of gas that is 36 light years across and contains large amounts of elements such as oxygen, neon, magnesium, silicon and sulfur.  Embedded in this cloud of multimillion degree gas is a key piece of evidence linking neutron stars and supernovae produced by the collapse of massive stars.

Standing out at higher X-ray energies, astronomers found a point-like source surrounded by features strikingly similar to those found around the Crab Nebula and Vela pulsars.  These features, together with the X-ray spectrum of the central source and surrounding nebula, provide strong evidence that a rapidly spinning neutron star is responsible for the central observed X-radiation.

Astronomers believe that an oxygen-rich supernova explosion is triggered by the collapse of the core of a massive star to form a neutron star, releasing tremendous amounts of energy in the process.  “This finding is very important, since it would allow us to conclusively associate this young, oxygen-rich supernova remnant with a core collapse, massive star supernova explosion,” said John P. Hughes of Rutgers University, lead author of a paper describing the research which appeared in the October 1, 2001, issue of The Astrophysical Journal.

With an age estimated at 1,600 years, G292.0+1.8 is one of three known oxygen-rich supernovae in our galaxy. These supernovae are of great interest to astronomers because they are one of the primary sources of the heavy elements necessary to form planets and people.

Scattered throughout the image are bluish knots of emission containing material that is highly enriched in newly created oxygen, neon, and magnesium produced deep within the original star and ejected by the supernova explosion.  Elsewhere in the image one can trace whitish colored regions (like the thin, nearly horizontal filaments just above the purple nebula) and yellow regions (mainly around the periphery, best seen toward the upper right).  This material is of a more standard composition without the enrichment seen elsewhere and represents either the pre-existing surrounding matter or the outer layers of the star itself, lost at an earlier time before the star exploded as a supernova.

The research team, which also included Patrick Slane (Smithsonian Astrophysical Observatory), David Burrows, Gordon Garmire, and John Nousek (Penn State University), Charles Olbert and Jonathan Keohane (North Carolina School of Science and Mathematics), used the Advanced CCD Imaging Spectrometer instrument to observe G292.0+1.8 on March 11, 2000.

ACIS was conceived and developed for NASA by Penn State and MIT under Garmire's leadership. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. TRW, Inc., in Redondo Beach, Calif., is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, Mass.

Images associated with this release are available on the World Wide Web at:

http://chandra.harvard.edu

AND

http://chandra.nasa.gov

Credit: NASA/CXC/Rutgers/J. Hughes et al.

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Chandra-Hubble composite of Herbig Haro objects in Orion Nebula

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Herbig Haro objects

The image on the left is a Palomar Digital Sky Survey image of the region of the Orion Nebula that contains Herbig Haro objects known as HH1 and HH2. The inset, right, presents a zoom that shows the position of the X-ray source, the green circle, detected by Chandra in HH2, superimposed on a false-color optical image from the Hubble Space Telescope. Herbig Haro objects (HH) are clouds of dust and gas that are either part of high-speed jets of gas streaming away from very young stars, or clouds of gas that have been hit by such jets.

The detection of X-rays from HH2 implies that a 600,000 miles per hour jet is plowing into a slower moving cloud. The resulting shock wave heats gas to a million degrees Celsius. The young star producing the jet is heavily obscured and detectable only with infrared and radio telescopes. In the image on the left, It lies about halfway between HH2, and HH1, the small bright cloud above and to the right of HH2.

Credit: X-ray: NASA/JPL/S. Pravdo et al. Optical: left: PDSS; right: NASA/HST

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Chandra Image of 3C58 3C58, the Remains of a Supernova

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Chandra Image of 3C58 3C58, the Remains of a Supernova

Chandra's image of 3C58, the remains of a supernova observed on Earth in 1181 AD, shows a rapidly rotating neutron star embedded in a cloud of high energy particles. The data revealed that the neutron star, or pulsar, is rotating about 15 times a second, and is slowing down at the rate of about 10 microseconds per year.

A comparison of the rate at which the pulsar is slowing down and its age indicate that the 3C58 pulsar, one of the youngest known pulsars, is rotating just about as fast now as when it was formed. This is in contrast to the Crab pulsar, which was formed spinning much more rapidly and has slowed to about half its initial speed. Furthermore, the total X-ray luminosity of the 3C58 pulsar and its surrounding nebula is a thousand times weaker than that of the Crab and its surrounding nebula.

Scientists hope that further study of the similarities and differences in the behavior of these two pulsars, which are approximately the same ages, will shed light on the process by which they are formed, and how they pump energy into space for thousands of years after the explosion.

Credit: NASA/CXC/SAO/S. Murray et al.

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Nova Aquila

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Nova Aquila

Chandra observed Nova Aquila, an outburst caused by a thermonuclear explosion on the surface of a white dwarf star, four times from April 2000 through October 2000. In the October data astronomers detected a dramatic flare of X-rays and cyclical 40-minute pulsations - the first time either of these phenomena had been seen in X-rays. The pulsations are thought to come from the contraction and expansion of the outer layers of the white dwarf, but the cause of the 15 minute X-ray flare remains a mystery.

The artist's illustration depicts a classical nova binary system just before an explosion on the surface of the white dwarf. Classical novas occur in a system where a white dwarf closely orbits a normal, companion star. In this illustration, gas is flowing from the large red, companion star into a disk and then onto the white dwarf that is hidden inside the white area. As the gas flows ever closer to the white dwarf, it gets increasingly hotter, as indicated by the change in colors from yellow to white. When the explosion occurs, it engulfs the disk of gas and the red companion star.

Credit: CXC/M. Weiss

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Chandra Image of Pulsar B1509-58

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Chandra Image of Pulsar B1509-58

This Chandra image gave astronomers their first view of the energetic and complex nebula surrounding the young pulsar PSR B1509-58. The blue and purple colors indicate X-rays emitted by high-energy particles of matter and anti-matter which stream away from the pulsar. The pulsar itself is the bright white source at the center of the nebula.

A thin jet, almost 20 light years in length, extends to the lower left, and traces a beam of particles being shot out from the pulsar's south pole at more than 130 million miles per hour. Just above the pulsar can be seen a small arc of X-ray emission, which marks a shock wave produced by particles flowing away from the pulsar's equator.

The green cloud near the top of the image is due to multimillion degree Celsius gas. This gas, possibly a remnant of the supernova explosion associated with the creation of the pulsar, may have been heated by collisions with high-energy particles produced by the pulsar.

Credit: NASA/MIT/B. Gaensler et al.

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Chandra Image of EMSS 1358+6245 galaxy cluster

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Chandra Image of EMSS 1358+6245 galaxy cluster

The cluster of galaxies EMSS 1358+6245 about 4 billion light years away in the constellation Draco is shown in this Chandra image. When combined with Chandra's X-ray spectrum, this image allowed scientists to determine that the mass of dark matter in the cluster is about four times that of normal matter.

The relative percentage of dark matter increases toward the center of the cluster. Measuring the exact amount of the increase enabled astronomers to set limits on the rate at which the dark matter particles collide with each other in the cluster. This information is extremely important to scientists in their quest to understand the nature of dark matter, which is thought to be the most common form of matter in the universe.

Credit: NASA/MIT/J. Aradbadjis et al.

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An X-ray Flare in Sagittarius A - The Center of our Galaxy

This false-color image shows the central region of our Milky Way Galaxy as seen by NASA's Chandra X-ray Observatory. The bright, point-like source at the center of the image was produced by a huge X-ray flare that occurred in the vicinity of the supermassive black hole at the center of our galaxy. This central black hole has about 2.6 million times the mass of our Sun and is associated with the compact radio source Sagittarius A. During the observation the X-ray source at the galactic center brightened dramatically in a few minutes, and after about three hours, rapidly declined to the pre-flare level. The rapid variation in X-ray intensity indicates that the flare was due to material as close to the black hole as the Earth is to the sun. This is the most compelling evidence yet that matter falling toward the black hole is fueling energetic activity in the galactic center.

Credit: NASA/MIT/F. Baganoff et al.

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The blue dots represent galaxies far beyond our Milky Way.

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This Chandra image marks the deepest X-ray look at the "zone of avoidance" — a region of space behind which no optical observation has ever been taken because thick clouds of dust and gas in the spiral arms of the Milky Way block visible radiation. X-rays, along with certain radio and infrared wavelengths, can penetrate this barrier, and Chandra provided the best look yet at what X-rays reveal. The diffuse blue emission is due to hot (ten million degree Celsius) gas concentrated along the plane of the Galaxy.

Most of the pink and red objects sources in this image are believed to be to be active stars in our Milky Way galaxy. The blue objects, referred to as "hard" sources because they emit more energetic X-rays, are considered to be distant galaxies. Because astronomers were able to identify these objects as being well beyond the galactic plane, they were able to determine that the X-ray glow from the galactic plane comes not from individual sources, but from the hot diffuse gas.

Chandra observed this region of the galactic plane in the constellation Scutum on February 25-26, 2000, with its Advanced CCD Imaging Spectrometer instrument for a total exposure time of 90,000 seconds.

Credit: NASA/GSFC/K. Ebisawa et al.

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Chandra and Hubble composite image of spiral galaxy NGC 4631

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Chandra and Hubble composite image of spiral galaxy NGC 4631

This image shows central region of the spiral galaxy NGC 4631 as seen edge-on from NASA's Chandra X-ray Observatory and the Hubble Space Telescope. The Chandra data, shown in blue and purple, provide the first unambiguous evidence for a halo of hot gas surrounding a galaxy that is very similar to our Milky Way. The structure across the middle of the image and the extended faint filaments, shown in orange, represents the observation from Hubble that reveal giant bursting bubbles created by clusters of massive stars. Scientists have debated for more than 40 years whether the Milky Way has an extended corona, or halo, of hot gas. Observations of NGC 4631 and similar galaxies provide astronomers with an important tool in the understanding our own galactic environment.

A team of astronomers, led by Daniel Wang of the University of Massachusetts at Amherst, observed NGC 4631 with Chandra's Advanced CCD Imaging Spectrometer (ACIS) instrument. The observation took place on April 15, 2000, and its duration was approximately 60,000 seconds.

PHOTO: NASA Marshall Center

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NGC 7027 nebula

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Chandra's image of NGC 7027 represents the first detection of X-rays from this young planetary nebula that is about 3,000 light years from Earth.

PHOTO: NASA Marshall Center

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Chandra and Hubble composite image of the Arches star cluster

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Chandra and Hubble composite image of the Arches star cluster

This composite image shows the first halo of X-ray emission detected around a young cluster of stars, known as the Arches cluster. The Chandra data is seen as the diffuse blue emission in the inset box and represent the 60-million-degree gas that envelopes the multitude of young stars in the cluster. The Chandra data overlay a Hubble Space Telescope infrared image of the same region, in which some of the individual stars in the cluster can be seen as point-like sources. Both the X-ray and infrared observations are then shown in context of the spectacular filamentary structures that appear in radio wavelengths displayed in red. The Arches cluster contains about 150 hot and young stars concentrated within a distance of about one light year, making it the most compact cluster of stars in our Galaxy. Many of these stars are 20 times as massive as the Sun and live short, furious lives that last only a few million years. Studies of the Arches cluster, located about 25,000 light years from Earth, can be used to learn more about the environments of "starburst" galaxies, which are millions of light years away and thus more difficult to resolve.

Credit: X-ray: NASA/CXC/Northwestern/F. Zadeh et al. IR: NASA/HST/NICMOS

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Chandra image of "The Antennae" galaxies

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Chandra image of "The Antennae" galaxies

This Chandra X-ray image shows the central regions of two colliding galaxies known collectively as "The Antennae." The latest Chandra data reveal a large population of extremely bright X-ray sources in this area of intense star formation. These "ultraluminous" X-ray sources, which emit 10 to several hundred times more X-ray power than similar sources in our own galaxy, are believed to be either massive black holes, or black holes that are beaming their energy toward Earth. In this X-ray image, red represents the low energy band, green intermediate and blue the highest observed energies. The white and yellow sources are those that emit significant amounts of both low- and high-energy X-rays. The Antennae galaxies, about 60 million light years from Earth in the constellation Corvus, got their nickname from the wispy antennae-like streams of gas seen by optical telescopes. These wisps are believed to have been produced by the collision between the galaxies that began about 100 million years ago and is still occurring.

Credit: NASA/SAO/CXC/G. Fabbiano et al.

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A cloud of gas and dust may be common to all quasars, but only visible at certain angles.

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This illustration demonstrates the possible different points-of-view from which astronomers observe quasars with X-ray satellites. If a quasar is oriented so that an observer's vantage point looks straight down the top of a quasar, then their view will not be obscured by the "donut" of gas and dust surrounding the core. This is the situation that astronomers believe occurs in "normal" quasars. However, 10 percent of quasars appear to absorb a great deal of their own radiation, including low-energy X-rays. Recent data from Chandra indicate that "shrouded" quasars appear this way because they are oriented so that astronomers are looking through the side of the obscuring ring of hot gas and dust. However, Chandra reveals that the underlying supermassive black holes behave like other quasars, and suggests that all quasars are the same types of object but just viewed from different angles. Credit: CXC/M. Weiss

PHOTO: NASA Marshall Center

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47 Tucanae

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47 Tucanae

This Chandra image provides the first complete census of compact binary stars in the core the globular cluster known as 47 Tucanae. As the oldest stellar systems in the Milky Way Galaxy, globular clusters are laboratories for stellar and dynamical evolution. Nearly all objects in the Chandra images are "binary systems," in which a normal, Sun-like star companion orbits a collapsed star, either a white dwarf or neutron star. The data also reveal the presence of "millisecond pulsars" that rotate extremely rapidly, between 100 to nearly 1,000 times a second. The relative numbers and components of the binary systems tell scientists about the formation and evolution of the globular cluster.

In a region of the sky equivalent to 1/15th the diameter of the full Moon, this Chandra image shows over 100 X-ray sources, more than ten times found by previous X-ray satellites. Astronomers have long studied 47 Tucanae, but Chandra is the first X-ray satellite with enough the spatial resolution and sensitivity to detect all of these objects.

The different colors in the Chandra image represent the dominant X-ray energy range for each source: low-energy X-ray emission (red sources), intermediate energy X-ray emission (green sources), and high-energy X-ray emission (blue sources). The white sources are bright in each energy range. The faint red sources are mostly millisecond pulsars, while the bright white sources are mostly binaries containing white dwarfs pulling matter off normal stars. The two blue sources are also binaries containing white dwarfs. Pairs of normal stars that have undergone large flares induced by their close proximity are shown objects with a mixture of red and white.

Scale:
Left: 2 arcmin per side
Right: 0.6 arcmin per side

Credit: NASA/CfA/J. Grindlay et al.

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Chandra image the inner portion of the Circinus Galaxy

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Chandra image the inner portion of the Circinus Galaxy

This Chandra X-ray image shows the inner portion of the Circinus Galaxy, with north at the top of the image and east to the left. In terms of X-ray energies, red represents low energy, green intermediate and blue the highest observed energies. The emission is resolved into a number of distinct components, many of which are associated with a central black hole. A bright, compact emission source is present at the center of the image. That nuclear source is surrounded by a diffuse X-ray halo that extends out several hundred light years. The X-rays directly to the northwest of the nucleus appear red, indicating predominantly soft energies, while the X-rays to the southeast are blue, indicating only hard energies.

Because low X-ray energies are absorbed by gas more easily than higher energies, the sharp contrast suggests that the red emission to the northwest originates from the near side of the disk of the Circinus Galaxy. And, the blue emission is more highly absorbed and must come from the gas within the disk or on the far side. Such geometry corresponds to the disk of the galaxy as seen in optical and radio images. A bright, soft X-ray plume of emission extends approximately 1,200 light years (380 parsecs) to the northwest and coincides with an optical region containing gas ionized by the nucleus. There is a very strong correlation between the X-ray emission and the high-excitationionized gas seen in emission-line images obtained by the Hubble Space Telescope and ground-based telescopes. The X-ray image was made with NASA's Chandra X-ray Observatory and the Advanced CCD Imaging Spectrometer (ACIS) from 67,000 seconds of exposure time on June 6-7, 2000.

Scale: 80 arcsec per side

Credit: NASA/Penn State/F. Bauer et al.

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Chandra image

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Chandra image of XTE J1118+480 black hole binary system

This Chandra X-ray Observatory image is a spectrum of a black hole, which is similar to the colorful spectrum of sunlight produced by a prism. The X-rays of interest are shown here recorded in the bright stripe that runs rightward and leftward from the center of the image. These X-rays are sorted precisely according to their energy with the highest-energy X-rays near the center of the image and the lower-energy X-rays farther out. The spectrum was obtained by using the Low Energy Transmission Grating (LETG), which intercepts X-rays and changes their direction by the amounts that depend sensitively on the X-ray energy. The LETG activated by swinging an assembly into position behind the mirrors and in front of the instrument that detects the X-rays. The assembly holds 540 gold transmission gratings: when in place behind the mirrors, the gratings intercept the X-rays reflected from the telescope. The bright spot at the center is due to a fraction of the X-ray radiation that is not deflected by the LETG. The spokes that intersect the central spot and the faint diagonal rays that flank the spectrum itself are artifacts due to the structure that supports the LETG grating elements.

A team of scientists led by Jeffrey McClintock (Harvard-Smithsonian Center for Astrophysics) used the LETG in conjunction with the Advanced CCD Imaging Spectrometer (ACIS) detector to observe the black hole binary system known as XTE J1118+480 for 27,000 seconds on April 18, 2000. This "X-ray nova," so-called because it goes through long periods of X-ray activity and then dormancy, contains a Sun-like star orbiting a black hole.

Photo: NASA/CfA/J. McClintock et al.

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Chandra Deep Field South

This one-million-second image, known as the "Chandra Deep Field South" since it is located in the Southern Hemisphere constellation of Fornax, is the deepest X-ray exposure ever achieved. Most of the objects seen in the Chandra Deep Field South are active galaxies and quasars powered by massive black holes. Also in this Chandra Deep Field South image, for the first time in such deep exposures astronomers detect X-rays from many galaxies, groups, and clusters of galaxies. The intensities of the X-rays in this image are depicted, from lowest to highest energies, by red, yellow, and blue respectively.

Another early exciting discovery to emerge from the Chandra Deep Field South is the detection of an extremely distant X-ray quasar shrouded in gas and dust. The discovery of this object, some twelve billion light years away, is key to understanding how dense clouds of gas form galaxies with massive black holes at their centers.

Chandra ACIS image

Photo: NASA/JHU/AUI/R. Giacconi et al.

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Chandra image of the Hubble Deep Field-North

Shown is an extremely deep Chandra X-ray Observatory image of the Hubble Deep Field-North (HDF-N), the most intensively studied patch of the night sky at all wavelengths from radio to X-ray. This image is thus the best combination of the deepest imaging capabilities available in both the optical and X-ray regimes.

Twelve X-ray sources are detected in the HDF-N. The false colors represent the "X-ray color" of the objects. Objects that appear redder are cooler in the X-ray band, while objects which are more blue are hotter in the X-ray band. About half of the sources show strong evidence that the X-rays are due to accretion onto supermassive black holes. The other sources have much lower luminosities, and in several cases are fairly nearby. In these galaxies, the Chandra X-ray detection is most likely the summed emission from a handful (or even one) bright sources within the galaxy, such as stellar-size black holes in binary star systems, the hot gas within the galaxy, or the remnants of supernova explosions. Chandra is thus now peering far enough into the universe to detect the type of X-ray emission that one finds in "normal" galaxies such as the Milky Way. This allows us to look back several billion years to see what our own galaxy and neighborhood (the Local Group) might have been like at earlier times.

Chandra ACIS image

Photo: NASA/PSU/G. Garmire, N. Brandt, et al.

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Hubble Deep Field-North (left) and the Chandra Deep Field-North (right)

This side-by-side presentation of the Hubble Deep Field-North (left) and the Chandra Deep Field-North (right) clearly demonstrates the importance of looking at the Universe in both the optical and X-ray regimes.

Twelve X-ray sources are detected in the HDF-N. The false colors represent the "X-ray color" of the objects. Objects that appear more red are cooler in the X-ray band, while objects that appear more blue are hotter in the X-ray band. About half of the sources show strong evidence that the X-rays are due to accretion onto supermassive black holes. The other sources have much lower luminosities, and in several cases are fairly nearby. In these galaxies, the Chandra X-ray detection is most likely the summed emission from a handful (or even one) bright sources within the galaxy, such as stellar-size black holes in binary star systems, the hot gas within the galaxy, or the remnants of supernova explosions. Chandra is thus now peering far enough into the universe to detect the type of X-ray emission that one finds in "normal" galaxies such as the Milky Way. This allows us to look back several billion years to see what our own galaxy and neighborhood (the Local Group) might have been like at earlier times.

Chandra ACIS image

Photo: NASA/PSU/G. Garmire, N. Brandt, et al.

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Chandra image of HGC 62 galaxy group

A new Chandra image shows remarkable detail and complexity in the central region of the compact galaxy group known as HGC 62. Such galaxy groups, which contain fewer galaxies than the better-known galaxy clusters, are an important class of objects because they may serve as cosmic building blocks in the large-scale structure of the Universe. After galaxies themselves form in the early Universe, such groups of galaxies may be the next systems to evolve. Later, it is believed, these groups of galaxies may combine with each other to form the bigger galaxy clusters. Most galaxies in the present-day Universe are still in groups or poor clusters. Our own Milky Way Galaxy, along with about two dozen other galaxies, including the Andromeda Nebula (M31) and the Large and Small Magellanic Clouds, is part of a galaxy group known as the Local Group.

A team of scientists, led by Jan Vrtilek (Harvard-Smithsonian Center for Astrophysics), observed HGC 62 with Chandra for about 50,000 seconds with the Advanced CCD Imaging Spectrometer. The range of X-ray surface brightness is represented in this image by various colors: green depicts the lower-brightness regions while purple and reddish indicate increasing X-ray intensity.

Chandra is an excellent tool to study the intragroup gas (the material between the galaxies) since this medium is too hot (roughly ten million degrees Celsius) to emit any significant radiation at optical wavelengths, but instead radiates most strongly in X-rays. Chandra also offers by far the highest angular resolution of any X-ray telescope to date, which is essential for showing the detailed structure of a complex source such as HCG 62. Hence, this X-ray observation provides a unique window for determining the physical characteristics of the galaxy group. Perhaps the most striking features of this X-ray image of HCG 62 are the two cavities that appear nearly symmetrically opposite one another (upper left and lower right) in the hot, X-ray emitting gas. These cavities might be explained by the presence of X-ray absorbing material, but are more likely due to jets of particles recently emitted from the core of NGC 4761, the central elliptical galaxy of HGC 62, although no such jets are visible today.

Scale: 4 arcmin per side

PHOTO: NASA/CfA/J. Vrtilek et al.

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Galaxy cluster 3C294

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This Chandra image shows hot gas enveloping the extremely distant galaxy known as 3C294. Astronomers believe this is the most distant cluster of galaxies ever detected in X-rays, capturing it when the universe was only 20 percent of its current age. The existence of such a faraway cluster may have important implications for how the universe evolved.

Chandra's image reveals an hourglass-shaped region of X-ray emission centered on the previously known central radio source (seen in the Chandra image as the blue central object) that extends outward for 60,000 light-years. The vast clouds of this hot gas that surround such galaxies in clusters are thought to be heated by collapse toward the center of the cluster. Until Chandra, X-ray telescopes have not had the needed sensitivity to identify such distant clusters of galaxies.

The intensity of the X-rays in this Chandra image of 3C294 is shown as red for low energy X-rays, green for intermediate, and blue for the most energetic X-rays. Chandra observed 3C294 for 5.4 hours on October 29, 2000, with the Advanced CCD Imaging Spectrometer.

PHOTO: NASA/IoA/A. Fabian et al.

Scale: 1.2 arcmin per side

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Sagittarius A East

This Chandra X-ray image shows the relationship between the black hole Sagittarius A* and the supernova remnant Sagittarius A East, both of which are located in the center of our galaxy in the constellation Sagittarius. For the first time, astronomers using Chandra were able to separate the supernova remnant, Sagittarius A East, from other complex structures in the center of the Milky Way. The emission from the supernova Sagittarius A East is depicted by the bright yellow and orange tones in the middle of this image. From the Chandra image, scientists can clearly see that Sagittarius A East surrounds Sagittarius A*, the Milky Way’s central black hole found near the white dots in the lower-right portion of the central object.

With Chandra, astronomers found hot gas concentrated within the larger radio shell of Sgr A East. The gas is highly enriched by heavy elements, with four times more calcium and iron than the Sun, and that confirms earlier suspicions that Sagittarius A East is most likely a remnant of a supernova explosion. While dozens of supernova remnants are known in our galaxy, the proximity of Sagittarius A East to the black hole in the center of our galaxy makes it important. By detailing the association between Sagittarius A East and Sagittarius A*, astronomers hope to learn if this is an example of a common relationship between supernovae and black holes throughout the Universe.

Chandra observed Sagittarius A* and Sagittarius A East on September 21, 1999, with the Advanced CCD Imaging Spectrometer (ACIS).

Credit: NASA/Penn State/G.Garmire et al.

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Solar-B

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NGC 3603

NGC 3603 is a bustling region of star birth in the Carina spiral arm of the Milky Way galaxy, about 20,000 light-years from Earth. For the first time, this Chandra image resolves the multitude of individual X-ray sources in this star-forming region. (The intensity of the X-rays observed by Chandra are depicted by the various colors in this image. Green represents lower intensity sources, while purple and red indicate increasing X-ray intensity.) Specifically, the Chandra image reveals dozens of extremely massive stars born in a burst of star formation about two million years ago.

This region's activities may be indicative of what is happening in other distant "starburst" galaxies (bright galaxies flush with new stars). In the case of NGC 3603, scientists now believe that these X-rays are emitted from massive stars and stellar winds, since the stars are too young to have produced supernovae or have evolved into neutron stars. The Chandra observations of NGC 3603 may provide new clues about X-ray emission in starburst galaxies as well as star formation itself.

PHOTO: NASA/GSFC/M.Corcoran et al.

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Chandra uncovers new evidence for event horizons surrounding black holes

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Chandra uncovers new evidence for event horizons surrounding black holes

Top: Gas from the companion star is drawn by gravity onto the black hole in a swirling pattern. As the gas nears the event horizon, a strong gravitational redshift makes it appear redder and dimmer. When the gas finally crosses the event horizon, it disappears from view. Because of this, the region within the event horizon appears black.

Bottom: As above, gas from the companion star flows down onto the collapsed star--in this case a neutron star instead of a black hole. As the gas approaches the neutron star, a similar gravitational redshift makes the gas appear redder and dimmer. However, when the gas strikes the solid surface of the neutron star, it glows brightly.

Credit: CXC/M. Weiss

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NGC6543 Cat's Eye Nebula

Left image: The X-ray data from the Chandra X-ray Observatory have revealed a bright central star surrounded by a cloud of multimillion-degree gas in the planetary nebula known as the Cat's Eye. This Chandra image, where the intensity of the X-ray emission is correlated to the brightness of the orange coloring, captures the expulsion of material from a star that is expected to collapse into a white dwarf in a few million years. The intensity of X-rays from the central star was unexpected, and it is the first time astronomers have seen such X-ray emission from the central star of a planetary nebula. The ACIS X-ray camera aboard Chandra observed NGC 6543 on May 10-11, 1999, for a total exposure time of 46,000 seconds.

Right image: This composite image of Chandra and Hubble Space Telescope data offers astronomers an opportunity to compare where the hotter, X-ray emitting gas appears in relation to the cooler material seen in optical wavelengths. The Chandra team found that the chemical abundances in the region of hot gas (its X-ray intensity is shown in purple) were not like those in the wind from the central star and different from the outer cooler material (the red and green structures.) Although still incredibly energetic and hot enough to radiate X-rays, Chandra shows the hot gas to be somewhat cooler than scientists would have expected for such a system. These results present a puzzle since the temperature of the X-ray emitting material suggests that mixing might have occurred. This discrepancy means some other process has created the "lukewarm" X-ray emission observed by Chandra. The color composite of optical and X-ray images was made by Zoltan G. Levay (Space Telescope Science Institute). The optical images were taken by J.P. Harrington and K.J. Borkowski (University of Maryland) with the Hubble Space Telescope.

Chandra image credit: (NASA/UIUC/Y. Chu et al.)
Hubble Space Telescope image credit: (NASA/HST)

Image scale: 30 arcsec each side

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Chandra image of supernova remnant IC443

This Chandra image reveals a point-like source of X-rays embedded in the remains of the supernova remnant IC443. This discovery was made by three high school students using data from NASA’s Chandra X-ray Observatory in conjunction with radio data from the National Science Foundation’s Very Large Array (VLA). The comet-shaped appearance of the cloud of high-energy particles in the Chandra image indicates that the neutron star is moving through IC443.

Like the wake of a supersonic airplane, the swept-back shape of the nebula around the neutron star allowed the students to measure the speed it is traveling away from its origin. Using this result and the apparent distance that the neutron star has traveled from the center of the supernova remnant, the students calculated that the light from the initial explosion arrived at Earth about 30,000 years ago, thus addressing an outstanding question about IC443.

The remnant of the IC443 supernova is a well-studied object. Astronomers have searched this region (roughly 5,000 light years from Earth) for the neutron star created in the explosion that they thought should be there, judging from the size and dynamics of the supernova remnant.

Neutron stars, such as the one found by the NCSSM team, are the compact hot embers of very massive stars that have exhausted their fuel and expelled their own shells. The remaining cores, often no more than 10 miles in diameter, are very dense objects that sometimes spin and release beams of particles along their magnetic poles.

The colors in this image represent the intensities of X-rays Chandra observed. The less energetic X-rays are represented by the reddish color, while the more energetic radiation is seen in the blue-green. The field of view in this image is approximately 1 arcminute across.

Credit: NASA/NCSSM/C. Olbert et al

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Supernova remnant known as G11.2-0.3

This Chandra image clearly locates a pulsar exactly at the geometric center of the supernova remnant known as G11.2-0.3. Chandra provides very strong evidence that the pulsar was formed in the supernova of 386 AD, which was witnessed by Chinese astronomers. Determining the true ages of astronomical objects is notoriously difficult, and for this reason, historical records of supernovae are of great importance. If confirmed, this will be only the second pulsar to be clearly associated with a historic event.

Since pulsars are known to move rapidly away from where they are formed, ChandraÕs ability to pinpoint the pulsar at the center of the remnant implies the system must be very young, since not enough time has elapsed for the pulsar to travel far from its birthplace. The Chandra observations of G11.2-0.3 have also, for the first time, revealed the bizarre appearance of the pulsar wind nebula at the center of the supernova remnant. Its rough cigar-like shape is in contrast to the graceful arcs observed around the Crab and Vela pulsars. However, together with those pulsars, G11.2-0.3 demonstrates that such complicated structures are ubiquitous around young pulsars.

Chandra observed G11.2-0.3 with the Advanced CCD Imaging Spectrograph at two epochs: August 6, 2000, and October 15, 2000, for approximately 20,000 and 15,000 seconds respectively.

Credit: NASA/McGill/V. Kaspi et al.

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A cooling flow in the Galaxy Cluster Abell 1795

Like a spoon moving through hot soup, the massive elliptical galaxy near the top of this image has cut a swath across the dense, hot gas in this crowded galaxy cluster known as Abell 1795. This smoothed Chandra X-ray Observatory image of the galaxy cluster A1795 shows a bright filament some 200,000 light years in length. The gas in this structure is denser and cooler (30 million compared to 50 million degrees) than the surrounding gas. The filament was most likely caused when an enormous elliptical galaxy (white spot at the head of the filament) moved through the cluster core. Hot gas spread throughout the cluster is drawn by the gravitational field of the giant galaxy into a cosmic wake of cooling gas, which appears as the long string-like feature in the middle of this image.

Most observed galaxies in the Universe appear in groups ranging from simple pairs and trios to complex clusters of thousands. Scientists find these clusters immersed in haloes of hot gas. Through time, this "intracluster" gas loses energy through X-ray radiation, cools, and flows toward the dense core of a cluster where it may form stars. This phenomenon is known as a "cooling flow."

The latest Chandra research on Abell 1795 was conducted by a team led by Professor Andrew Fabian of the Institute of Astronomy, Cambridge, England, using the Advanced CCD Imaging Spectrometer (ACIS) instrument aboard. Chandra observed Abell 1795 for 19,594 seconds on December 20, 1999, and then for 19,421 seconds on March 21, 2000.

(Photo: NASA/loA/AC Fabian et al.)

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Zeta Orionis

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Zeta Orionis

This figure is a composite of the X-ray spectrum and CCD image of Zeta Orionis, one of the three belt stars in the constellation of Orion. The Advanced CCD Imaging Spectrometer (ACIS) image (upper right) clearly shows that Zeta Orionis is a binary, or, double, star system. The recent results by Waldron and Cassinelli focused on the larger "A" component of the system. The spatial resolution between the "A" and "B" elements of Zeta Orionis are a mere 2.4 arc seconds away from one another, demonstrating the fantastic resolution capable by the Chandra X-ray Observatory. The color contours in the image are scaled logarithmically in relationship to their X-ray intensities.

The X-ray emission line spectrum (lower left) represents the Chandra High-Energy Transmission Grating Medium Energy Grating observation of Zeta Orionis "A". By determining the wavelength associated with each emission line, scientists can identify the atomic species and their states of ionization, which can be used to determine the temperature range of the plasma. Furthermore, by measuring the relative line strengths of certain ions, scientists can extract densities and specific temperatures of the X-ray emitting plasma. One major difference between this O-star spectrum and that of other stars such as the Sun is that the X-ray emission lines are significantly broader, indicating a larger dispersion in plasma velocities.

Chandra X-ray Observatory ACIS/HETG images.

Credit: NASA/CXC/Waldron & Cassinelli

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Quasar 3C273

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Quasar 3C273

This Chandra image shows important new details in the powerful jet shooting from the quasar 3C273, providing an X-ray view into the area between 3C273’s core and the beginning of the jet. High-powered jets driven from quasars, often at velocities very close to the speed of light, have long been perplexing for scientists. Instead of seeing a smooth stream of material driven from the core of the quasar, most optical, radio, and earlier X-ray observations have revealed inconsistent, "lumpy" clouds of gas. The recent Chandra data show a continuous X-ray flow in 3C273 from the core to the jet, which may reveal insight on the physical processes that power these jets. Scientists would like to learn why matter is violently ejected from the quasar’s core, then appears to suddenly slow down.

The energy emitted from the jet in 3C273 probably comes from gas that falls toward a supermassive black hole at the center of the quasar, but is redirected by strong electromagnetic fields into a collimated jet. While the black hole itself is not observed directly, scientists can discern properties of the black hole by studying the jet. The formation of the jet from the matter that falls into the black hole is a process that remains poorly understood.

Chandra X-ray Observatory ACIS/HETG images

Credit: NASA/CXC/H. Marshall et al.

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Chandra image of Sirius A and B

This Chandra X-ray image offers a new view of the Sirius star system located 8.6 light years from Earth. This image shows two sources and a spike-like pattern due to the support structure for the transmission grating. The bright source is Sirius B, a white dwarf star with a surface temperature of about 45,000 degrees Fahrenheit (25,000 Celsius), which produces very low-energy X-rays. The dim source at the position of Sirius A — a normal star more than twice as massive as the sun — may be due to ultraviolet radiation from Sirius A leaking through the filter on the detector.

In contrast, Sirius A is the brightest star in the northern sky when viewed with an optical telescope, while Sirius B is 10,000 times dimmer. Because the two stars are so close together Sirius B escaped detection until 1862 when Alvan Clark discovered it while testing one of the best optical telescopes in the world at that time.

The theory of white dwarf stars was developed by S. Chandrasekhar, the namesake of the Chandra X-ray Observatory. The story of Sirius B came full cycle when it was observed by Chandra in October 1999 during the calibration or test period.

The white dwarf, Sirius B, has a mass equal to the mass of the sun, packed into a diameter that is 90% that of the Earth. The gravity on the surface of Sirius B is 400,000 times that of Earth.

Credit: NASA/SAO/CXC

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Chandra clinches case for missing link black hole

X-ray image of the central region of the starburst galaxy M82. Of particular interest is the bright source near the center of the image, offset from the dynamical center (small green +) of the galaxy by about 600 light years. This source was seen to increase dramatically in intensity over a period of three months, as indicated by comparing the left image to the more-recent observation at right. Short-term flickering in 10-minute intervals also was observed. This fast flickering and the peak intensity of the source are strong evidence that the X-rays are produced by matter accreting onto a black hole with the mass of more than 500 suns.

This is the first confirmed case of such a large black hole outside the nucleus of a galaxy, and is believed to represent a new type of black hole formed by the merger of scores of black holes, or by the collapse of a "hyperstar" formed by the coalescence of many stars.

Chandra observed M82 six times for a total of approximately 30 hours. Some of the observations were made with the High Resolution Camera (HRC) and some with the Advanced CCD Imaging Spectrometer (ACIS) X-ray camera.

Scale: 30 arcsec on a side.

Credit: NASA/CXC/SAO

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Alt text

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This figure is a composite of the X-ray spectrum and CCD image of Zeta Orionis, one of the three belt stars in the constellation of Orion. The Advanced CCD Imaging Spectrometer (ACIS) image (upper right) clearly shows that Zeta Orionis is a binary, or, double, star system. The recent results by Waldron and Cassinelli focused on the larger "A" component of the system. The spatial resolution between the "A" and "B" elements of Zeta Orionis are a mere 2.4 arc seconds away from one another, demonstrating the fantastic resolution capable by the Chandra X-ray Observatory. The color contours in the image are scaled logarithmically in relationship to their X-ray intensities.

The X-ray emission line spectrum (lower left) represents the Chandra High-Energy Transmission Grating Medium Energy Grating observation of Zeta Orionis "A". By determining the wavelength associated with each emission line, scientists can identify the atomic species and their states of ionization, which can be used to determine the temperature range of the plasma. Furthermore, by measuring the relative line strengths of certain ions, scientists can extract densities and specific temperatures of the X-ray emitting plasma. One major difference between this O-star spectrum and that of other stars such as the Sun is that the X-ray emission lines are significantly broader, indicating a larger dispersion in plasma velocities.

Chandra X-ray Observatory ACIS/HETG images.

Credit: NASA/CXC/Waldron & Cassinelli

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Chandra image of colliding galaxies

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This Chandra image of colliding galaxies shows superbubbles produced by the combined effect of thousands of supernovae, as well as dozens of bright point-like sources produced by neutron stars and black holes.

Photo: NASA

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Chandra X-ray Observatory image of Comet C/1999 S4 (LINEAR)

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Chandra X-ray Observatory image of Comet C/1999 S4 (LINEAR). On July 14, 2000, the Chandra X-ray Observatory imaged the comet repeatedly for a total of 2 hours and detected X-rays from oxygen and nitrogen ions. The details of the X-ray emission, as recorded on Chandra's Advanced CCD Imaging Spectrometer, show the X-rays are produced by collisions of ions racing away from the Sun (solar wind) with gas in the comet.

Credit: NASA/SAO/CXC/STScI/Lisse et al.

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Brown Dwarf LP 944-20

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The first flare ever seen from a brown dwarf, or failed star, has been detected by the Chandra X-ray Observatory. For the first nine hours and 36 minutes of Chandra's observation, no X-rays were detected from Brown Dwarf LP 944-20 (left panel). Then the brown dwarf turned on with a bright X-ray flare (right) that gradually diminished over the last few hours of the observation. The grainy appearance of the image on the right is due to a shorter exposure time. The bright dots in the background are other X-ray sources, seven of which have been identified as stars.

Credit: NASA

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A new 14-hour Chandra observation of the supernova remnant Cassiopeia A (Cas A) gives the best map yet of heavy elements ejected in a supernova explosion. All images are 8.5 arc minutes on a side, corresponding to 28.2 light years at a distance of 11,000 light years. These images are designed to show the distribution of some of the elements ejected in the explosion that produced Cas A. The elements are part of a gas that has a temperature of about 50 million degrees Celsius. The colors represent intensity of X-rays, with yellow the most intense, then red, purple, and green.
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Chandra X-ray image of the supernova remnant Cassiopeia casa1.jpg

The broadband image, which shows all the X-rays detected from Cas A, is more symmetric than the others. This could be due to the presence of X-rays from synchrotron radiation by extremely high energy particles spiraling in the magnetic field of the remnant, or to shock waves traveling through material puffed off thousands of years before the supernova.

Credits: NASA/GSFC/U. Hwang et al.
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Chandra X-ray image of the supernova remnant Cassiopeia casa2.jpg


The silicon image shows a bright, broad jet breaking out of the upper left side of the remnant, and faint streamers in an opposite direction. This jet could be due to an asymmetry in the explosion.

Credits: NASA/GSFC/U. Hwang et al.


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Chandra X-ray image of the supernova remnant Cassiopeia

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The calcium image is similar to the silicon image, but less bright and clumpier.

Credits: NASA/GSFC/U. Hwang et al.

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Chandra X-ray image of the supernova remnant Cassiopeia

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The iron image shows significant differences from other images. Since iron is the heaviest element shown, these maps support the suggestion that the layers of the star were overturned either before or during the explosion.

Credits: NASA/GSFC/U. Hwang et al.

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Chandra X-ray image of Perseus A

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Chandra X-ray image of Perseus A

Credit: NASA/CXO/SAO

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Chandra X-ray (left) and Hubble Space Telescope (right) image of the central region of the active galaxy NGC 4151.

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Chandra X-ray (left) and Hubble Space Telescope (right) image of the central region of the active galaxy NGC 4151.

Credit: NASA Marshall photo

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Chandra X-ray image of NGC 3783

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Chandra X-ray image of NGC 3783

The central bright spot in this image is the Chandra X-ray image of NGC 3783. The long intersecting lines represent a dispersed X-ray spectrum, or rainbow, produced by the medium (lower left to upper right) and high energy (upper left to lower right) gratings on Chandra.

Credit: NASA/PSU

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Hubble Deep Field North (optical), showing X-ray sources identified by Chandra.

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Hubble Deep Field North (optical), showing X-ray sources identified by Chandra.

Photo Credit: Optical: NASA/HST; X-ray: NASA/PSU

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Chandra image showing X-ray sources in Hubble Deep Field North and positions of submillimeter-emitting galaxies (boxes).

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Chandra image showing X-ray sources in Hubble Deep Field North and positions of submillimeter-emitting galaxies (boxes).

Photo Credit: NASA/PSU

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X-ray Jet Points Toward Cosmic Energy Booster Radio Galaxy Pictor A.

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X-ray Jet Points Toward Cosmic Energy Booster Radio Galaxy Pictor A.

The Chandra X-ray image of Pictor A shows a spectacular jet that emanates from the center of the galaxy (left) and extends across 360 thousand light years toward a brilliant hot spot. The hot spot is at least 800 thousand light years (8 times the diameter of our Milky Way galaxy) away from where the jet originates. The hot spot is thought to represent the advancing head of the jet, which brightens conspicuously where it plows into the tenuous gas of intergalactic space. One possible explanation for the X rays is that shock waves along the side and head of the X-ray jet are boosting electrons and possibly protons to speeds close to that of light. Jets are thought to be produced by the powerful electromagnetic forces created by magnetized gas swirling toward a black hole. Although most of the material falls into the black hole, some can be ejected at extremely high speeds. Magnetic fields spun out by these forces can extend over vast distances and may help explain the narrowness of the jet.

Chandra X-ray Observatory ACIS Image

Credit: NASA/UMD Scale: The hot spot is 4.2 arc minutes from the galaxy.

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Vela Pulsar

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Vela Pulsar

Credit: NASA Marshall photo

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Planetary Nebula BD+30

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Planetary Nebula BD+30

Credit: NASA Marshall photo

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SUPERNOVA 1987A in X-rays

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SUPERNOVA 1987A in X-rays

The Chandra X-ray Observatory image of SN 1987A made in January 2000 shows an expanding shell of hot gas produced by the supernova explosion. The gas in the shell has a temperature of about ten million degrees Celsius, and is visible only with an X-ray telescope. The colors represent different intensities of X-ray emission, with white being the brightest. Chandra X-ray Observatory ACIS image.

Scale: Field shown is 3 arcsec on a side, corresponding to a size of 2.4 light years.

Credit: NASA/CXC/SAO/PSU/D. Burrows et al

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Cygnus X-3 and Scattering Halo

Cygnus X-3 and Scattering Halo

Chandra shows new way to measure cosmic distances. A team of scientists has used Chandra to observe a halo around the X-ray source Cygnus X-3. The halo (beyond the yellow ring in the center) is due to scattering by interstellar dust grains along the line of sight to the source. The sharp horizontal line is an instrumental effect. The X-ray emission from Cygnus X-3 is due to matter falling from a normal star onto a nearby neutron star or black hole. Its X-ray emission varies regularly with a 4.8 hour period, as the compact star circles a companion star. The radiation from the halo is delayed and smeared out, so the variations are damped. By observing the delays and smearing at different parts of the halo, the distance to the X-ray source is found to be 30,000 light years. Chandra X-ray Observatory ACIS/HETG image. Scale: Field shown is 200 arcsec on a side.

Credit: NASA-MSFC/SRON/MPE

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Color composite of the supernova remnant E0102-72: X-ray (blue), optical (green), and radio (red).

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Color composite of the supernova remnant E0102-72: X-ray (blue), optical (green), and radio (red). E0102-72 is the remnant of a star that exploded in a nearby galaxy known as the Small Magellanic Cloud. The galaxy is approximately 190,000 light years from Earth, so we see the remnant as it was about 190,000 years ago -- about a thousand years after the explosion occurred. The star exploded outward at speeds in excess of 20 million kilometers per hour (12 million mph) and collided with surrounding gas. This collision produced two shock waves, or cosmic sonic booms -- one traveling outward, and the other rebounding back into the material ejected by the explosion. The radio image, shown in red, was made using the Australia Telescope Compact Array. The radio waves are due to extremely high energy electrons spiraling around magnetic field lines in the gas and trace the outward moving shock wave. The Chandra X-ray image, shown in blue, shows gas that has been heated to millions of degrees Celsius by the rebounding, or reverse shock wave. The X-ray data show that this gas is rich in oxygen and neon. These elements were created by nuclear reactions inside the star and hurled into space by the supernova. The Hubble Space Telescope optical image, shown in green, shows dense clumps of oxygen gas that have "cooled" to about 30,000 degree Celsius. Images such as these, taken with different types of telescopes, give astronomers a much more complete picture of supernova explosions. They can map how the elements necessary for life are dispersed, and measure the energy of the matter as it expands into the galaxy. Chandra X-ray Observatory Advanced CCD Imaging Spectrometer Image (ACIS) Reference: T. Gaetz et al, "Chandra X-ray Observatory Arsecond Imaging of the Young Oxygen-Rich Supernova Remnant 1E0102.2-7219", The Astrophysical Journal Letters (in press) (astro-ph/0003355).

Credit: X-ray (NASA/CXC/SAO); optical (NASA/HST); radio: (ACTA)

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Chandra Advanced Charged Coupled Imaging Spectrometer (ACIS) image (contours) and optical image (color pixels) of a newly discovered powerful X-ray source in a distant galaxy.

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Chandra Advanced Charged Coupled Imaging Spectrometer (ACIS) image (contours) and optical image (color pixels) of a newly discovered powerful X-ray source in a distant galaxy.

When viewed with an optical telescope, this galaxy appears normal. But when the Chandra X-ray Observatory observed the galaxy during calibration testing in September 1999, it discovered an unusually strong source of X-rays. Located 2.5 billion light years from Earth, the X-ray source is concentrated in the central regions of the galaxy and could be another example of a veiled black hole. This discovery adds to a growing body of evidence that our census of energetic black hole sources in galaxies is far from complete. A team of Italian and Harvard-Smithsonian scientists, led by Fabrizio Fiore of the Astronomical Observatory of Rome, and the Harvard-Smithsonian Center for Astrophysics, made the discovery. The vertical lines in the image are part of a grid to locate the source in the sky. The X-ray contours are consistent with a point-like source in the center of the galaxy. The colors in the optical image represent brightness levels. The source name is CXOUJ031238.9-765134, which defines its position in the sky.

Credits: X-ray: NASA/CXC/SAO Optical: ESO/La Silla

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Chandra X-ray image of Type 2 quasar (left) and Hubble optical image of same quasar.

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Chandra X-ray image of Type 2 quasar (left) and Hubble optical image of same quasar.

Credit: NASA/CXC/SAO

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Chandra X-ray Observatory image of the galaxy cluster Abell 2142.

Chandra X-ray Observatory image of the galaxy cluster Abell 2142.

The image shows a colossal cosmic "weather system" produced by the collision of two giant clusters of galaxies. For the first time, the pressure fronts in the system can be traced in detail, and they show a bright but relatively cool 50 million degree central region (white) embedded in large elongated cloud of 70 million degree gas (magenta), all of which is roiling in a faint "atmosphere" of 100 million degree gas (faint magenta and dark blue).

Abell 2142 is six million light years across and contains hundreds of galaxies and enough gas to make a thousand more. It is one of the most massive objects in the universe. Galaxy clusters grow to vast sizes as smaller clusters are pulled inward under the influence of gravity. They collide and merge over the course of billions of years, releasing tremendous amounts of energy that heats the cluster gas. The smoothness of the elongated cloud in the Chandra image suggests that these sub-clusters collided two or three times in a billion years or more, and have nearly completed their merger.

Chandra X-ray Observatory Advanced CCD Imaging Spectrometer Image

Credit: NASA/CXC/SAO

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The X-ray spectrum of the central region of the galaxy, NGC 5548

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CHANDRA READS THE COSMIC BAR CODE OF GAS AROUND A GIANT BLACK HOLE

This figure is the X-ray spectrum of the central region of the galaxy, NGC 5548. The spectrum shows the number of X rays present at each energy or wavelength, and amounts to a cosmic bar code. It allows scientists to take an inventory of the gas around the giant black hole in the center of the galaxy. The deep valleys in the spectrum are produced when a blanket of warm (few million degree) gas absorbs X rays of specific energies from hotter gas close to the central black hole.

Absorption lines, or valleys, due to the elements carbon, nitrogen, oxygen, neon and magnesium can be seen in the figure. A peak in the spectrum due to emission from oxygen is also identified. The Roman numerals refer to how many electrons have been stripped from the atoms. e.g. OVIII is an ion that has lost 7 electrons from its atomic shell, NeX has lost 9 electrons, etc. Detailed analysis shows that absorption lines from elements silicon, sodium, and iron are also present.

The exact position of the lines relative to laboratory standards shows that the lines are shifted systematically to shorter wavelengths by a fraction of a percent. This shift is due to the gas moving away from the source (Doppler effect). It indicates that the blanket of absorbing gas is flowing away from the black hole at about a million kilometers per hour (600,000 miles per hour), probably because of the enormous amount of energy radiated by the extremely hot gas very near the black hole. Chandra X-ray Observatory Low Energy Transmission Grating/High Resolution Camera Image.

Credit: NASA/SRON

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Chandra image of Andromeda galaxy

Chandra image of Andromeda galaxy

This X-ray image shows the central portion of the Andromeda Galaxy. The blue dot in the center of the image is a "cool" million-degree X-ray source where a supermassive black hole with the mass of 30-million suns is located. The X-rays are produced by matter funneling toward the black hole. Numerous other hotter X-ray sources also are apparent. Most of these are probably due to X-ray binary systems, in which a neutron star or black hole is in close orbit around a normal star.

(Credit: NASA/CXC/SAO/S. Murray, M. Garcia)

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Chandra X-ray image of M82

Chandra X-ray image of M82

M82, at a distance of 11 million light years from Earth, is the nearest starburst galaxy. Massive stars are forming and expiring in M82 at a rate 10 times higher than in our galaxy. The bright spots in the center are supernova remnants and X-ray binaries. These are some of the brightest such objects known. The luminosity of the X-ray binaries suggests that most contain a black hole. The diffuse X-ray light in the image extends over several thousand light years, and is caused by multimillion-degree gas flowing out of M82. A close encounter with a large galaxy, M81, in the last 100 million years is thought to be the cause of the starburst activity. Image made with the Advanced CCD Imaging Spectrometer (ACIS).

Credit: NASA/CXC/SAO/PSU/G. Garmire, R. Griffiths (CMU)

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Chandra X-ray image of Orion Nebula star cluster

Chandra X-ray image of Orion Nebula star cluster

This X-ray image shows about a thousand X-ray emitting young stars in the Orion Nebula star cluster. The X-rays are produced in the multimillion-degree upper atmospheres of these stars. At a distance of about 1,800 light years, this cluster is the closest massive star-forming region to Earth. It is well known in the night sky because it illuminates the Orion Nebula. The region shown in this image is about 10 light years across. The bright stars in the center are part of the Trapezium, an association of very young stars with ages less than a million years. The dark vertical and horizontal lines, and the streaks from the brightest stars are instrumental effects. Image made with the Advanced CCD Imaging Spectrometer (ACIS).

Credit: NASA/PSU/G. Garmire, E. Feigelson

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Chandra image of Milky Way center

Chandra image of Milky Way center

Chandra X-ray image of the innermost 10 light years at the center of our galaxy. The image has been smoothed to bring out the X-ray emission from an extended cloud of hot gas surrounding the supermassive black hole candidate Sagittarius A* (white dot at the center of the image). This gas glows in X-ray light because it has been heated to a temperature of millions of degrees by shock waves produced by supernova explosions and perhaps by colliding winds from young massive stars.

Credit: NASA/PSU/G.Garmire, F. Baganoff (MIT)

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Chandra X-ray image of supernova remnant E0102-72

Chandra X-ray image of supernova remnant E0102-72

(Credit: NASA/CXC/SAO)

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Chandra Image of Deep Field in Canes Venatici

Chandra Image of Deep Field in Canes Venatici

This Chandra X-ray Observatory image of a 27.7 hour observation of a region in the direction of the constellation Canes Venatici, close to the Big Dipper shows about 3 dozen X-ray sources. Some of the sources were too faint to be seen by optical telescopes such as the Hubble Space Telescope and the Keck 10 meter telescope in Hawaii. This new class of sources may represent some of the most distant objects ever detected. If this sample of the sky is typical, tens of millions of such sources must exist. Image made with the Advanced CCD Imaging Spectrometer (ACIS).

Credit: NASA/GSFC (Mushotzky et al.)

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Chandra X-ray image of the supernova remnant Cassiopeia

Chandra X-ray image of Cas A

The red, green, and blue regions in this Chandra X-ray image of the supernova remnant Cassiopeia A show where the intensity of low, medium, and high energy X-rays, respectively, is greatest. The red material on the left outer edge is enriched in iron, whereas the bright greenish white region on the lower left is enriched in silicon and sulfur. In the blue region on the right edge, low and medium energy X-rays have been filtered out by a cloud of dust and gas in the remnant. (Image made with the Advanced CCD Imaging Spectrometer (ACIS).

(Credit: NASA/CXC/SAO)

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Chandra observation of supernova SN1999em

Chandra observation of supernova SN1999em

In late October 1999, a supernova was detected in NGC 1637, a spiral galaxy that is 25 million light years from Earth. Chandra observed the supernova twice soon after the explosion. X-rays, shown by contours overlaid on an optical mage, were detected from 3 million degree gas produced by the supernova. An X-ray source in the center of the galaxy was also detected.

(Credit: X-ray: NASA/CXC/SAO; Optical: Palomar Observatory Digital Sky Survey)

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The newest image from the Chandra X-ray Observatory shows a "cosmic train wreck of colliding galaxies," says Dr. Martin Weisskopf, Chandra's chief project scientist at the Marshall Center. "The result is a beautiful laboratory where we can study the details of what happens in these collisions."

NASA Marshall Photo # hydraDEC7.jpg

The newest image from the Chandra X-ray Observatory shows a "cosmic train wreck of colliding galaxies," says Dr. Martin Weisskopf, Chandra's chief project scientist at the Marshall Center. "The result is a beautiful laboratory where we can study the details of what happens in these collisions."

PHOTO CREDIT: NASA/CXC/SAO

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Chandra X-ray Observatory image of the distant galaxy 3C295

NASA Marshall Photo # 3c295.jpg

NASA’s new Chandra X-ray Observatory image of the distant galaxy 3C295 shows it as an explosive galaxy — possibly the result of being enveloped by a vast gas cloud containing more than 100 galaxies. Astronomers believe an excess of matter falling into a massive black hole triggered the explosion — hurling an enormous release of energy back into the gas cloud. This energy, or X-radiation, is highlighted in this colorized image.

PHOTO CREDIT: NASA/CXC/SAO

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Centaurus A

NASA Marshall Photo # CXO_CenA.jpg

Object Name: Centaurus A Galaxy

Centaurus A At a distance of 11 million light years, Centaurus A or NGC 5128, is the nearest example of a type of galaxy called an active galaxy. It is a large elliptically shaped galaxy that shows evidence of repeated explosions, probably from a supermassive black hole in the center of the galaxy. Radio and Chandra X-ray images of the galaxy show a jet of high energy particles blasting out from the center. Because of its unusual nature and proximity, it is one of the most extensively studied galaxies in the southern hemisphere.

PHOTO CREDIT: NASA/CXC/SAO

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Eta Carinae

NASA Marshall Photo # eCAR1200dpi.jpg

Object Name: Eta Carinae

The Chandra X-ray Observatory image shows the complex nature of the region around Eta Carinae, a massive supergiant star that is 7,500 light years from Earth. The outer horseshoe shaped ring has a temperature of about 3 million degrees Kelvin. It is about two light years in diameter and was probably caused by an outburst that occurred more than a thousand years ago. The blue cloud in the inner core is three light months in diameter and is much hotter. The white area, less than a light month in diameter, is the hottest and may contain the superstar.

PHOTO CREDIT: NASA/CXC/SAO

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Comparison of Eta Carinae Images

NASA Marshall Photo # eCAR1200dpi_t.jpg

Object Name: Eta Carinae

Chandra X-ray image of Eta Carinae, the most luminous star known in our galaxy, as compared to an optical image by the Hubble Space Telescope.

PHOTO CREDIT: NASA/Hubble

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Crab Nebula

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Object Name: Crab Nebula

The Chandra X-ray image of the Crab Nebula shows the central pulsar surrounded by tilted rings of high-energy particles that appear to have been flung outward over a distance of more than a light year from the pulsar. Perpendicular to the rings, jet-like structures produced by high-energy particles blast away from the pulsar.

PHOTO CREDIT: NASA/CXC/SAO

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Supernova Remnant E0102-72

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Object Name: E0102-72

Object Category: Supernova Remnant Coordinates: (J2000) Right Ascension 01h04m02s Declination -72d01m56s Constellation: Tucana (Tuc)

Object Description: E0102-72 is a supernova remnant in the Small Magellanic Cloud, a satellite galaxy of the Milky Way. This galaxy is 190,000 light years from Earth. E0102 -72, which is approximately a thousand years old, is believed to have resulted from the explosion of a massive star. Stretching across forty light years of space, the multi-million degree source resembles a flaming cosmic wheel. Astronomer's Notebook: ACIS detector

PHOTO CREDIT: Chandra X-ray Image

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Supernova remnant Coordinates G21.5-0.9

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Object Name: G21.5-0.9

Object Category: Supernova remnant Coordinates: (J2000) Right Ascension 18h33m34s Declination -10d34m7s Constellation: Scutum (Sct)

Object Description: The identification of G21.5-0.9 as the remnant of a supernova explosion is based on indirect evidence from radio and x-ray observations. At both radio and x-ray wavelengths, it appears as round patch in the sky. Detailed observations with radio telescopes confirm that the radio waves are produced by high energy electrons spiraling around magnetic field lines (synchrotron radiation). The x-rays are probably produced by the same process, but the electrons involved have energies many thousands times higher than those that produce the radio waves. The favored theory is that the high energy electrons responsible for both the radio and x-ray emission are produced by a rapidly rotating, highly magnetized neutron star left behind when a massive star exploded some 40,000 years ago.

Astronomer's Notebook: ACIS detector

PHOTO CREDIT: Chandra X-ray Image

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Neutron star/Supernova Remnant PSR 0540-69

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Object Name: PSR 0540-69


Object Category: Neutron star/Supernova Remnant Coordinates: (J2000) Right Ascension 05h40m11s Declination -69d19m55s Constellation: Dorado (Dor)

Object Description: PSR 0540-69 is a neutron star, or pulsar, that is rotating very rapidly, making a complete rotation every one-twentieth of a second. It is similar in many ways to the famous Crab Nebula pulsar. Both objects are spinning rapidly, are about 1,000 years old and are surrounded by a large cloud of gas and high energy particles. The surrounding cloud in both cases is powered by the conversion of rotational energy of the neutron star into high energy particles through the combined action of rapid rotation and a strong magnetic field. PSR 0540-69 is 180,000 light years away in the Large Magellanic Cloud, one of the Milky Way's small satellite galaxies.

Astronomer's Notebook: HRC detector

PHOTO CREDIT: Chandra X-ray Image

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Cassiopeia A, Chandra X-ray Image

CXO_CassiopeiaA.jpg

Cassiopeia A, Chandra X-ray Image

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Cassiopeia A, Rosat X-ray

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Cassiopeia A, Rosat X-ray

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Cassiopeia A, optical telescope

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Cassiopeia A, optical telescope

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PKS 0637-752 Quasar, Chandra X-ray Image

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PKS 0637-752 Quasar, Chandra X-ray Image

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Scientists at the Chandra X-ray Observatory Control Center in Cambridge, Mass., react to the first images recorded by the telescope.

Chandra Reaction.jpg

Scientists at the Chandra X-ray Observatory Control Center in Cambridge, Mass., react to the first images recorded by the telescope.

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Scientists at the Chandra X-ray Observatory Control Center in Cambridge, Mass., react to the first images recorded by the telescope.

Chandra Reaction2.jpg

Scientists at the Chandra X-ray Observatory Control Center in Cambridge, Mass., react to the first images recorded by the telescope.

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Scientists at the Chandra X-ray Observatory Control Center in Cambridge, Mass., react to the first images recorded by the telescope.

Chandra Reaction3.jpg

Scientists at the Chandra X-ray Observatory Control Center in Cambridge, Mass., react to the first images recorded by the telescope.

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Scientists at the Chandra X-ray Observatory Control Center in Cambridge, Mass., react to the first images recorded by the telescope.

Chandra Reaction4.jpg

Scientists at the Chandra X-ray Observatory Control Center in Cambridge, Mass., react to the first images recorded by the telescope.

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Scientists at the Chandra X-ray Observatory Control Center in Cambridge, Mass., react to the first images recorded by the telescope.

Chandra Reaction5.jpg

Scientists at the Chandra X-ray Observatory Control Center in Cambridge, Mass., react to the first images recorded by the telescope.

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