Chandra looks at the aftermath of a massive star explosion
NASA’s Chandra X-ray Observatory has captured a spectacular image of
G292.0+1.8, a young, oxygen-rich supernova remnant with a pulsar at
its center surrounded by outflowing material. Astronomers know that
pulsars are formed in supernova explosions, but they are currently unable
to identify what types of massive stars must die in order for a pulsar
to be born. Now that Chandra has revealed strong evidence for a pulsar
in G292.0+1.8, astronomers can use the pattern of elements seen in the
remnant to make a much closer connection between pulsars and the massive
stars from which they form.
This Chandra image shows a rapidly expanding shell of gas that is 36
light years across and contains large amounts of elements such as oxygen,
neon, magnesium, silicon and sulfur. Embedded in this cloud of multimillion
degree gas is a key piece of evidence linking neutron stars and supernovae
produced by the collapse of massive stars.
Standing out at higher X-ray energies, astronomers found a point-like
source surrounded by features strikingly similar to those found around
the Crab Nebula and Vela pulsars. These features, together with the
X-ray spectrum of the central source and surrounding nebula, provide
strong evidence that a rapidly spinning neutron star is responsible
for the central observed X-radiation.
Astronomers believe that an oxygen-rich supernova explosion is triggered
by the collapse of the core of a massive star to form a neutron star,
releasing tremendous amounts of energy in the process. “This finding
is very important, since it would allow us to conclusively associate
this young, oxygen-rich supernova remnant with a core collapse, massive
star supernova explosion,” said John P. Hughes of Rutgers University,
lead author of a paper describing the research which appeared in the
October 1, 2001, issue of The Astrophysical Journal.
With an age estimated at 1,600 years, G292.0+1.8 is one of three known
oxygen-rich supernovae in our galaxy. These supernovae are of great
interest to astronomers because they are one of the primary sources
of the heavy elements necessary to form planets and people.
Scattered throughout the image are bluish knots of emission containing
material that is highly enriched in newly created oxygen, neon, and
magnesium produced deep within the original star and ejected by the
supernova explosion. Elsewhere in the image one can trace whitish colored
regions (like the thin, nearly horizontal filaments just above the purple
nebula) and yellow regions (mainly around the periphery, best seen toward
the upper right). This material is of a more standard composition without
the enrichment seen elsewhere and represents either the pre-existing
surrounding matter or the outer layers of the star itself, lost at an
earlier time before the star exploded as a supernova.
The research team, which also included Patrick Slane (Smithsonian Astrophysical
Observatory), David Burrows, Gordon Garmire, and John Nousek (Penn State
University), Charles Olbert and Jonathan Keohane (North Carolina School
of Science and Mathematics), used the Advanced CCD Imaging Spectrometer
instrument to observe G292.0+1.8 on March 11, 2000.
ACIS was conceived and developed for NASA by Penn State and MIT under
Garmire's leadership. NASA's Marshall Space Flight Center in Huntsville,
Ala., manages the Chandra program. TRW, Inc., in 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.
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