NASA Goddard Space Flight Center,
|March 19, 2003
NASA's High-Energy Transient Explorer
(HETE) satellite image of the birth of a black hole.
Scientists arriving on the scene of a gamma-ray burst just moments
after the explosion, have witnessed the death of a gigantic star
and the birth of something monstrous in its place, quite possibly
a brand new, spinning black hole.
The burst observation, featured in the March 20 issue of Nature,
is the most detailed to date. The observation confirms that gamma-ray
bursts announce the demise of the most massive stars in the universe,
a theory called the collapsar model. NASA's High-Energy Transient
Explorer (HETE), ground-based robotic telescopes, and fast-thinking
researchers around the globe, made the prompt observation possible.
"This stunning observation places us in the fiery throes of
a star explosion, peering through the debris at a newly formed black
hole within," said Dr. Anne Kinney, NASA director for astronomy
and physics, Headquarters, Washington.
"If a gamma-ray burst is the birth cry of a black hole, then
the HETE satellite has just allowed us into the delivery room,"
said Dr. Derek Fox of the California Institute of Technology in
Pasadena, Calif., the lead author of the Nature paper.
Gamma-ray bursts shine hundreds of times brighter than a supernova,
or as bright as a million trillion suns. The mysterious bursts are
common, yet random and fleeting. The gamma-ray portion of a burst
typically lasts from a few milliseconds to 100 seconds. An afterglow,
caused by shock waves from the explosion sweeping up matter and
ramming this into the region around the burst, can linger for days
or weeks in lower-energy forms of light, such as X rays or visible
A gamma-ray burst, named GRB021004, appeared on October 4, 2002,
at 8:06 a.m. EDT. Wasting no time, HETE spotted the burst, nailed
down a location, and notified observers worldwide within a few seconds,
while the gamma rays were still pouring in. First on the scene was
the Automated Response Telescope (ART) in Wako, Japan, observing
the region just 193 seconds after the burst.
Fox pinpointed the afterglow shortly after this from images captured
by a telescope on Mt. Palomar, near San Diego. Then the race was
on, as scientists, using more than 50 telescopes, in California,
across the Pacific, Australia, Asia, and Europe zoomed in on the
afterglow before the approaching sunrise.
Scientists arrived on the scene of GRB021004 early enough to witness
an entirely new phenomenon: the ongoing energizing of the burst
afterglow for more than half an hour after the burst. This power
must have been provided by whatever object produced the gamma-ray
"Gamma-ray bursts must be many times more times powerful than
we previously thought," said Dr. George Ricker of the Massachusetts
Institute of Technology (MIT), Cambridge, Mass., principal investigator
for the HETE mission. "The gamma-ray portion of the burst is
perhaps just the tip of the iceberg," he said.
These findings support the collapsar model, where the core of a
massive star collapses into a black hole. The black hole's spin
or magnetic fields may be acting like a slingshot, flinging material
into the surrounding debris. Scientists calculated that GRB021004
originated from a star 15 times more massive than the Earth’s
Gamma-ray burst hunters are greatly aided by three new developments:
fast triggers from orbiting detectors; fast relays to observers
worldwide via the Gamma-ray burst Coordinates Network; and fast
responses from ground-based robotic telescopes. HETE is the first
satellite to provide and distribute accurate burst locations within
seconds. In December 2003, NASA will launch the Swift satellite,
which will have an even greater capability to detect and locate
bursts, as well as onboard optical, ultraviolet and X-ray telescopes.
Fox and his colleagues relied on data from ART in Japan, the Palomar
Oschin Telescope and the Near Earth Asteroid Tracking camera, which
are automated. HETE was built by MIT as a mission of opportunity
under the NASA Explorer Program, collaboration among U.S. universities,
Los Alamos National Laboratory, and scientists and organizations
in Brazil, France, India, Italy and Japan.
For high-quality animation and more information on the HETE program,
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