 |  | | | | NASA Hubble Space Telescope Detects Ring of Dark Matter - Multimedia Page
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05.15.07
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Presenter 1: + Dr. Myungkook James Jee, Johns Hopkins University, Baltimore
Image Above: This Hubble Space Telescope composite image shows a ghostly "ring" of dark matter in
the galaxy cluster Cl 0024+17.
The ring-like structure is evident in the blue map of the cluster's dark matter distribution.
The map is superimposed on a Hubble image of the cluster. The ring is one of the
strongest pieces of evidence to date for the existence of dark matter, an unknown
substance that pervades the universe.
The map was derived from Hubble observations of how the gravity of the cluster Cl
0024+17 distorts the light of more distant galaxies, an optical illusion called gravitational
lensing. Although astronomers cannot see dark matter, they can infer its existence by
mapping the distorted shapes of the background galaxies. The mapping also shows how
dark matter is distributed in the cluster.
Astronomers suggest that the dark-matter ring was produced from a collision between
two gigantic clusters.
Dark matter makes up the bulk of the universe's material and is believed to make up the
underlying structure of the cosmos.
The Hubble observations were taken in November 2004 by the Advanced Camera for
Surveys (ACS). Thanks to the exquisite resolution of the ACS, astronomers saw the
detailed cobweb tracery of gravitational lensing in the cluster.
Credit: NASA, ESA, M.J. Jee and H. Ford (Johns Hopkins University)
(Other Versions of this image: + Medium Image | + Large Image)
Presenter 2: Dr. Richard White, Space Telescope Science Institute, Baltimore
Image Above: This rich galaxy cluster, catalogued as Cl 0024+17, is allowing astronomers to probe the
distribution of dark matter in space. The blue streaks near the center of the image are the
smeared images of very distant galaxies that are not part of the cluster. The distant
galaxies appear distorted because their light is being bent and magnified by the powerful
gravity of Cl 0024+17, an effect called gravitational lensing.
Dark matter cannot be seen because it does not shine or reflect light. Astronomers can
only detect its influence by how its gravity affects light. By mapping the distorted light
created by gravitational lensing, astronomers can trace how dark matter is distributed in
the cluster. While mapping the dark matter, astronomers found a dark-matter ring near
the cluster's center. The ring's discovery is among the strongest evidence that dark matter
exists.
The Hubble observations were taken in November 2004 by the Advanced Camera for
Surveys.
Credit: NASA, ESA, M.J. Jee and H. Ford (Johns Hopkins University)
(Other Versions of this image: + Medium Image | + Large Image)
Presenter 3: Dr. Richard Massey, California Institute of Technology, Pasadena
Image Above: A rare and spectacular head-on collision between two galaxies appears in this NASA Hubble Space Telescope true-color image of the Cartwheel Galaxy, located 500 million light-years away in the constellation Sculptor. The new details of star birth resolved by Hubble provide an opportunity to study how extremely massive stars are born in large fragmented gas clouds.
The striking ring-like feature is a direct result of a smaller intruder galaxy — possibly one of two objects to the right of the ring — that careened through the core of the host galaxy. Like a rock tossed into a lake, the collision sent a ripple of energy into space, plowing gas and dust in front of it. Expanding at 200,000 miles per hour, this cosmic tsunami leaves in its wake a firestorm of new star creation. Hubble resolves bright blue knots that are gigantic clusters of newborn stars and immense loops and bubbles blown into space by exploding stars (supernovae) going off like a string of firecrackers.
The Cartwheel Galaxy presumably was a normal spiral galaxy like our Milky Way before the collision. This spiral structure is beginning to re-emerge, as seen in the faint arms or spokes between the outer ring and bulls-eye shaped nucleus. The ring contains at least several billion new stars that would not normally have been created in such a short time span and is so large (150,000 light-years across) our entire Milky Way Galaxy would fit inside.
Credit: NASA, ESA, and K. Borne (STScI)
(Other Versions of this image: + Large Image)
Presenter 1: + Dr. Myungkook James Jee, Johns Hopkins University, Baltimore
Image Above: Simulation of two galaxy clusters colliding. As the two clusters smash together, the dark matter falls to the center of the combined cluster and then back out. The dark matter moves outward, it begins to slow down under the pull of gravity and piles up, forming a "ring" of concentrated dark matter.
Credit: NASA, ESA, M.J. Jee (Johns Hopkins University), and G. Bacon (STScI)
(Click image to play movie or click here: + 320 x 240 mpg movie)
Image Above: Illustration showing two views of interacting galaxy clusters. On the left, there is a side view of the cluster collision and on the right, there is a cluster collision as seen from Earth.
Credit: NASA, ESA, M.J. Jee (Johns Hopkins University), and A. Feild (STScI)
(Other Versions of this image: + Large Image)
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