SETI bioastro: FW: Signs of an Ancient Supernova

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From: Larry Klaes (larry.klaes@incent.com)
Date: Fri May 18 2001 - 09:27:19 PDT


-----Original Message-----
From: History of Astronomy Discussion Group
[mailto:HASTRO-L@WVNVM.WVNET.EDU]On Behalf Of Jadran Kale
Sent: Friday, May 18, 2001 9:36 AM
To: HASTRO-L@WVNVM.WVNET.EDU
Subject: Signs of an Ancient Supernova

Signs of an Ancient Supernova

In the spring of 386 A.D., Chinese astronomers made note of a new star,
most likely a supernova, in the sky near Sagittarius, as the constellation
later came to be known. Its remnantsóan expanding ring of gas and
particlesówere found in the 1970s and named G11.2-0.3. Now a group of
Canadian researchers report that a pulsar in the area is probably left over
from the historic event as well. Using NASA's Chandra X-ray Observatory,
Victoria Kaspi and her colleagues at McGill University discovered that the
pulsar, a neutron star originally spotted in 1997, lies at the exact
geometric center of G11.2-0.3. They described their finding last week at
the American Astronomical Society meeting in San Diego.

The pulsar's precise location suggests that it was created during the
fourth-century explosion. If so, it is only the second such star associated
with a recorded supernova: the Crab Nebula is believed to have resulted
from the supernova in 1054 A.D. Based on the pulsar's spin rate of 14 times
per second, scientists at the Japanese Advanced Satellite for Cosmology and
Astrophysics (ASCA) estimated its age to be roughly 24,000 years old. But
if it is truly 1,615 years old, as the new research suggests, then pulsars
may spin more slowly than was expected. "We believe that the pulsar and the
supernova remnant G11.2-0.3 are both likely to be left over from the
explosion seen by the Chinese observers over 1,600 years ago," says Mallory
Roberts of McGill University. "While this is exciting by itself, it also
raises new questions about what we know about pulsars, especially during
their infancies."

http://www.sciam.com/news/011601/3.html


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