Stellar Forensics with Striking Image from Chandra (Forwarded)

Jennifer Morcone
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256/544-7199)

Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
(Phone: 617/496-7998)

For Release: October 23, 2007

Stellar Forensics with Striking Image from Chandra

A spectacular new image shows how complex a star's afterlife can be. By
studying the details of this image made from a long observation by NASA's
Chandra X-ray Observatory, astronomers can better understand how some
stars die and disperse elements like oxygen into the next generation of
stars and planets.

At a distance of about 20,000 light years, G292.0+1.8 is one of only three
supernova remnants in the Milky Way known to contain large amounts of
oxygen. The image shows a rapidly expanding, intricately structured,
debris field that contains, along with oxygen, other elements such as neon
and silicon that were forged in the star before it exploded.

"We are finding that, just like snowflakes, each supernova remnant is
complicated and beautiful in its own way," said Sangwook Park of Penn
State who led the work, released in conjunction with the "8 Years of
Chandra" symposium in Huntsville, Ala.

The new, deep Chandra image -- equaling nearly 6 days worth of observing
time -- shows an incredibly complex structure. Understanding the details
of G292.0+1.8 is especially important because astronomers have considered
it to be a "textbook" case of a supernova created by the death of a
massive star.

By mapping the distribution of X-rays in different energy bands, the
Chandra image traces the distribution of chemical elements ejected in the
supernova. The results imply that the explosion was not symmetrical. For
example, blue (silicon and sulfur) and green (magnesium) are seen strongly
in the upper right, while yellow and orange (oxygen) dominate the lower
left. These elements light up at different temperatures, indicating that
the temperature is higher in the upper right portion of G292.0+1.8.

Slightly below and to the left of the center of G292.0+1.8 is a pulsar, a
dense, rapidly rotating neutron star that remained behind after the
original star exploded. Assuming that the pulsar was born at the center of
the remnant, it is thought that recoil from the lopsided explosion may
have kicked the pulsar in this direction.

Surrounding the pulsar is a so-called pulsar wind nebula, a magnetized
bubble of high-energy particles. The narrow, jet-like feature running from
north to south in the image is likely parallel to the spin axis of the
pulsar. This structure is most easily seen in high energy X-rays. In the
case of G292.0+1.8, the spin direction and the kick direction do not
appear to be aligned, in contrast to apparent spin-kick alignments in some
other supernova remnants.

Another intriguing feature of this remnant is the bright equatorial belt
of X-ray emission that extends across the center of the remnant. This
structure is thought to have been created when the star -- before it died
-- expelled material from around its equator via winds. The orientation of
the equatorial belt suggests that the parent star maintained the same spin
axis both before and after it exploded.

"The detection of the pulsar and its wind nebula confirms that the
supernova that led to G292 produced a neutron star through the collapse of
the core of a massive star," said coauthor John Hughes of Rutgers
University, "The ability to study the asymmetry of the original explosion
using X-ray images of the remnant gives us a powerful new technique for
learning about these cataclysmic events."

These results will appear in an upcoming issue of The Astrophysical
Journal Letters. NASA's Marshall Space Flight Center, Huntsville, Ala.,
manages the Chandra program for the agency's Science Mission Directorate.
The Smithsonian Astrophysical Observatory controls science and flight
operations from the Chandra X-ray Center in Cambridge, Mass.

Additional information and images are available at:

http://chandra.harvard.edu/photo/2007/g292/
and
http://chandra.nasa.gov