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 the outer parts of the ring at a
speed of 4,500 kilometers per second (10 million miles per hour). The
gas behind the shock wave has a temperature of 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, in University Park, Pa., 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,
according to which 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, 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 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, University Park. The High Energy Transmission
Grating was built by the Massachusetts Institute of Technology. NASA’s
Marshall Space Flight Center in Huntsville, Ala., manages the Chandra
program. TRW, Inc., 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.
For images connected to this
release, and to follow Chandra’s progress, visit the Chandra sites at:
and
