Dolores Beasley
Headquarters, Washington, DC                   May 11, 2000
(Phone: 202/358-1753)

Steve Roy
Marshall Space Flight Center, Huntsville, AL 
(Phone: 256/544-6535)

Dr. Wallace Tucker
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA
(Phone: 617/496-7998)

RELEASE:  00-77

IMPACT! CHANDRA IMAGES A YOUNG SUPERNOVA BLAST WAVE

     Two images made by NASA's Chandra X-ray Observatory, 
one in October 1999, the other in January 2000, show for 
the first time the full impact of the actual blast wave 
from Supernova 1987A (SN1987A). The observations are the 
first time that X-rays from a shock wave have been imaged 
at such an early stage of a supernova explosion.

     Recent observations of SN 1987A with the Hubble Space 
Telescope revealed gradually brightening hot spots from a 
ring of matter ejected by the star thousands of years 
before it exploded. Chandra's X-ray images show the cause 
for this brightening ring. A shock wave is smashing into 
portions of the ring at a speed of 10 million miles per 
hour (4,500 kilometers per second). The gas behind the 
shock wave has a temperature of about ten million degrees 
Celsius, and is visible only with an X-ray telescope.

     "With Hubble we heard the whistle from the oncoming 
train," said David Burrows of Pennsylvania State 
University, University Park, the leader of the team of 
scientists involved in analyzing the Chandra data on SN 
1987A. "Now, with Chandra, we can see the train."

     The X-ray observations appear to confirm the general 
outlines of a model developed by team member Richard McCray 
of the University of Colorado, Boulder, and others, which 
holds that a shock wave has been moving out ahead of the 
debris expelled by the explosion. As this shock wave 
collides with material outside the ring, it heats it to 
millions of degrees. "We are witnessing the birth of a 
supernova remnant for the first time," McCray said.

     The Chandra images clearly show the previously unseen, 
shock-heated matter just inside the optical ring. 
Comparison with observations made with Chandra in October 
and January, and with Hubble in February 2000, show that 
the X-ray emission peaks close to the newly discovered 
optical hot spots, and indicate that the wave is beginning 
to hit the ring. 

     In the next few years, the shock wave will light up 
still more material in the ring, and an inward moving, or 
reverse, shock wave will heat the material ejected in the 
explosion itself. "The supernova is digging up its own 
past," said McCray. 

     The observations were made on October 6, 1999, using 
the Advanced CCD Imaging Spectrometer (ACIS) and the High 
Energy Transmission Grating, and again on January 17, 2000, 
using ACIS. Other members of the team were Eli Michael of 
the University of Colorado; Dr. Una Hwang, Dr. Steven Holt 
and Dr. Rob Petre of NASA's Goddard Space Flight Center in 
Greenbelt, MD; and Professors Gordon Garmire and John 
Nousek of Pennsylvania State University. The results will 
be published in an upcoming issue of the Astrophysical 
Journal. 

     The ACIS instrument was built for NASA by the 
Massachusetts Institute of Technology, Cambridge, and 
Pennsylvania State University.  The High Energy 
Transmission Grating was built by the Massachusetts 
Institute of Technology. NASA's Marshall Space Flight 
Center in Huntsville, AL, manages the Chandra program. TRW, 
Inc., Redondo Beach, CA, is the prime contractor for the 
spacecraft. The Smithsonian's Chandra X-ray Center controls 
science and flight operations from Cambridge, MA.

     Images to illustrate this release and more information 
on Chandra's progress can be found on the Internet at:

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

                            -end-