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Nancy Neal
Headquarters, Washington         April 10, 2003
(Phone: 202/358-2369)

David Aguilar
Harvard-Smithsonian Center for Astrophysics, Cambridge, 
Mass.
(Phone: 617/495-7462)

RELEASE: 03-135

NASA HELPS LINK GAMMA RAY BURST & SUPERNOVA

     Scientists have discovered one of the brightest and 
closest gamma ray bursts on record is also a supernova. 
Scientists obtained the first direct evidence linking these 
two types of explosions, both triggered by the death of a 
massive star. 

NASA's High-Energy Transient Explorer satellite (HETE) 
initially detected the burst on March 29, 2003, in the 
constellation Leo. For more than 30 seconds, the burst 
outshone the entire universe in gamma rays, and its optical 
afterglow was still more than a trillion times brighter than 
the sun two hours later. 

Through observations of the gamma ray burst afterglow, 
astronomers spotted the telltale signs of a supernova. 
Scientists cannot yet determine which came first, the burst 
or the supernova, but the same event, a star explosion, was 
certainly the trigger for both. 

"There should no longer be doubt in anybody's mind that 
gamma ray bursts and supernovae are connected," said Dr. 
Thomas Matheson of the Harvard-Smithsonian Center for 
Astrophysics (CfA), Cambridge, Mass., and a member of the 
team that made the discovery. 

Matheson's colleagues include Dr. Peter Garnavich of Notre 
Dame and Dr. Krzysztof Stanek of the CfA. Nearly two-dozen 
scientists, primarily using the Multiple Mirror Telescope 
(MMT) at Mount Hopkins, Ariz., obtained the data. When the 
burst was discovered, astronomers scheduled to use the MMT 
agreed to observe it as a target of opportunity in 
collaboration with Garnavich, Matheson and Stanek. 

Gamma ray bursts are the most powerful explosions in the 
universe, and they likely signal the birth of black holes. 
Bursts occur at random locations scattered across the sky. 
Few last more than a minute, making them hard to study. 

A supernova is the explosion of a star at least eight times 
as massive as the sun. When such stars deplete their nuclear 
fuel, they no longer have the energy to support their mass. 
Their cores implode, forming either a neutron star or, if 
there is enough mass, a black hole. The surface layers of 
the star blast outward, forming the colorful patterns 
typical of supernova remnants. 

Previous observations, particularly from NASA's Chandra X-
ray Observatory, have provided convincing indirect evidence 
of the gamma ray burst/supernova connection. The Chandra 
Observatory detected iron and other heavy elements, which 
are formed in supernovae, in the vicinity of gamma ray 
bursts. 

Matheson and the others detected direct evidence the burst 
afterglow's light is exhibiting the same patterns as light 
from a supernova. Namely, the scientists see changes in 
light absorbed by silicon and iron atoms, forged in the 
supernova, as the afterglow slowly fades away. The team is 
continuing to observe and analyze this unique burst. 

"Scores of observatories, and even more observers, are now 
studying this event," said Dr. Donald Kniffen, at NASA 
Headquarters in Washington. "We've been searching for a 
direct link for decades, and we finally got it," he said. 

"All gamma ray bursts may have associated supernovae that 
are too faint to observe," Matheson said. The March 29 
burst, named GRB 030329, was one of the closest to Earth. It 
was approximately two billion light-years away, as opposed 
to other bursts located more than 10 billion light-years 
away. Because the burst was both relatively close to Earth 
and bright, the supernova was detectable. 

The Massachusetts Institute of Technology in Cambridge, 
Mass., as a mission of opportunity under the NASA Explorer 
Program, with collaboration among U.S. universities; Los 
Alamos (N.M.) National Laboratory; scientists and 
organizations in Brazil, France, India, Italy and Japan, 
built HETE. 

For more information about NASA, HETE and CfA on the 
Internet, visit:

http://www.nasa.gov

http://space.mit.edu/HETE/

http://www-cfa.harvard.edu/

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