X-rays From A Young Supernova Remnant
More than fifty years ago, a supernova was discovered in M83, a spiral galaxy
about 15 million light years from Earth. Astronomers have used NASA's Chandra
X-ray Observatory to make the first detection of X-rays emitted by the debris
from this explosion.
Named SN 1957D because it was the fourth supernova
to be discovered in the year 1957, it is one of only a few located outside of
the Milky Way galaxy that is detectable, in both radio and optical wavelengths,
decades after its explosion was observed. In 1981, astronomers saw the remnant
of the exploded star in radio waves, and then in 1987 they detected the remnant
at optical wavelengths, years after the light from the explosion itself became
undetectable.
A relatively short observation -- about 14 hours long --
from NASA's Chandra X-ray Observatory in 2000 and 2001 did not detect any X-rays
from the remnant of SN 1957D. However, a much longer observation obtained in
2010 and 2011, totaling nearly 8 and 1/2 days of Chandra time, did reveal the
presence of X-ray emission. The X-ray brightness in 2000 and 2001 was about the
same as or lower than in this deep image.
This new Chandra image of M83
is one of the deepest X-ray observations ever made of a spiral galaxy beyond our
own. This full-field view of the spiral galaxy shows the low, medium, and
high-energy X-rays observed by Chandra in red, green, and blue
respectively.
The new X-ray data from the remnant of SN 1957D provide
important information about the nature of this explosion that astronomers think
happened when a massive star ran out of fuel and collapsed. The distribution of
X-rays with energy suggests that SN 1957D contains a neutron star, a rapidly
spinning, dense star formed when the core of pre-supernova star collapsed. This
neutron star, or pulsar, may be producing a cocoon of charged particles moving
at close to the speed of light known as a pulsar wind nebula.
If this
interpretation is confirmed, the pulsar in SN 1957D is observed at an age of 55
years, one of the youngest pulsars ever seen. The remnant of SN 1979C in the
galaxy M100 contains another candidate for the youngest pulsar, but astronomers
are still unsure whether there is a black hole or a pulsar at the center of SN
1979C.
Image Credits: X-ray: NASA/CXC/STScI/K.Long et al., Optical:
NASA/STScI