The bright, unstable star Eta Carinae may
explode at any time.
This result has been suggested by the behavior
of recently discovered supernova SN2006gy,
the brightest stellar explosion ever seen. Eta Carinae lies at a relatively
short distance from earth, 7.500 light years, and is considered to be consuming
nuclear fuel at a rapid rate. Upon exploding, it will be quite visible from
Earth, perhaps matching the moon in brilliance.
Eta Carinae, 100-150 times more massive than
the Sun, lives in an unstable equilibrium where the star's gravity almost
balances the outward pressure of intense radiation generated internally. Slight
perturbations of the star might eject enormous quantities of surface matter. In
the 1840s, Eta Carinae had a massive eruption, ejecting more than 10 times the
mass of the sun, briefly becoming the second brightest star in the sky, and
miraculously surviving the disruption.
New data from NASA's Chandra
X-ray Observatory and the Hubble Space Telescope shows the remnants of that
titanic event. Blue regions show the cool optical emission from the dust and
gas thrown off the star. This debris forms a bipolar shell around the star,
which lies near the brightest point of the optical emission, surrounded by a
ragged cloud of fainter material. An unusual jet points from the star to the
upper left.
X-ray emissions (orange and yellow) are produced
as material thrown off Eta Carinae impacts nearby gas and dust, heating gas to
temperatures over a million degrees. This hot shroud extends far beyond the
cooler, optical nebula.
Eta Carinae has a companion not directly
visible in these images, but X-ray variability close to the star signals its
presence. The role of the companion in the life of Eta Carinae remains unknown.
--NASA and SPACE.com Staff
Credit: X-ray:
NASA/CXC/GSFC/M.Corcoran et al.; Optical: NASA/STScI
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