We need a non-WTC story, so here:
Cool star chills stellar theories
By Richard Stenger CNN
from http://www.cnn.com/2001/TECH/space/09/10/cool.star/index.html
(CNN) -- A star besieged by unbelievably hot waves of nuclear explosions is
ten times cooler than expected, forcing astronomers to rethink their ideas
about stellar physics.
For more than a decade, the energy of billions of hydrogen bombs per second
battered a neutron star near the center of our galaxy.
Months after the assault ended, an astrophysicist used the Chandra X-ray
Observatory to take the temperature of the beleaguered star, only to find
that it burned no hotter than nearby stars that escaped the energy
onslaught.
"Twelve years of constant thermonuclear explosions. One would think that
would heat things up," said Rudi Wijnands of the Massachusetts Institute of
Technology.
"This leaves us wondering whether some neutron stars are in the freezer for
a much longer time than previously thought ... or whether they cool down
incredibly fast."
Neutron stars are the remnants of massive stars that explode in supernova.
The dying stars shed their outer layers while their interiors implode and
collapse into dense cores, which exert intense gravitational force.
Like other neutron stars, this particular one, known as KS 1731-260, draws
gaseous material or fuel from a healthy companion star.
The swirling material from the donor star collides into the neutron star,
setting off glowing explosions of intense X-ray energy.
Such gas siphoning periods can last for weeks or years. Astronomers expected
KS 1731-260 to be particularly hot at the end of a 12-year episode, but it
turned out to be only about the same temperature as neutron stars that
consumed fuel from a neighbor for a week or month.
Astronomers have few clues as to why. Perhaps the neutron star was in a deep
freeze for much longer than astronomers imagined.
"We may have identified a new type of neutron star system that can lie
dormant for thousands of years," said fellow MIT astronomer Walter Lewin.
Wijnands announced his findings last week at a conference marking the second
anniversary of Chandra, the most powerful X-ray telescope in orbit.
This archive was generated by hypermail 2b30 : Fri Oct 12 2001 - 14:40:28 MDT