[meteorite-list] The jury's still out on the wink

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Fri, 25 May 2007 00:44:50 -0500
Message-ID: <nqtc53hsehe8o4q5ok5qs359uda2ev967g_at_4ax.com>

http://space.newscientist.com/article/dn11928-our-solar-system-started-with-a-nudge-not-a-bang.html

Our solar system started with a nudge, not a bang
19:00 24 May 2007
NewScientist.com news service
Zeeya Merali

Our solar system came into existence with a nudge, rather than a bang, according
to a meteorite analysis that rules out a popular theory for the formation of our
planetary system.

Most astrophysicists believe that the solar system formed from a cloud of gas
and dust when a nearby supernova exploded, compressing the dust and triggering
the birth of the Sun and planets, says Martin Bizzarro of the University of
Copenhagen in Denmark.

To investigate, Bizzarro and his colleagues looked for iron-60, an isotope
produced by supernovae, in meteorites that formed during the first million years
in the solar system's history. "To our great surprise, there was no iron-60,
ruling out the supernova trigger mechanism," says Bizzarro.

The team found another isotope, aluminium-26, suggesting an alternative trigger.
Aluminium-26 only forms in extremely massive stars, around 30 times the mass of
the Sun, and such stars release a great amount of energy in winds loaded with
aluminium-26, says Bizzarro. These winds could have buffeted the gas cloud,
causing the solar system to form, he says.

There was also evidence of iron-60 in meteorites dating from a few million years
later, suggesting that this massive star exploded at a later date, injecting
iron-60 into the youthful solar system.

The team are now looking for evidence of other supernovae in our solar system's
vicinity. "This could have been a very crowded and dynamic neighbourhood," says
Bizzarro.

Journal reference: Science (vol 316, p 1178)
Received on Fri 25 May 2007 01:44:50 AM PDT