[meteorite-list] Supernova radioisotopes show sun was born in star cluster

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Thu Oct 5 02:02:27 2006
Message-ID: <1s79i29m8r6ig8ppt2l0sp4bg6il3g198b_at_4ax.com>

http://www.physorg.com/news79190228.html

Supernova radioisotopes show sun was born in star cluster

The death of a massive nearby star billions of years ago offers evidence the sun
was born in a star cluster, say astronomers at the University of Illinois at
Urbana-Champaign. Rather than being an only child, the sun could have hundreds
or thousands of celestial siblings, now dispersed across the heavens.

In a paper accepted for publication in the Astrophysical Journal, astronomy
professors Leslie W. Looney and Brian D. Fields, and undergraduate student John
J. Tobin take a close look at short-lived radioactive isotopes once present in
primitive meteorites. The researchers' conclusions could reshape current
theories on how, when and where planets form around stars.

Short-lived radioactive isotopes are created when massive stars end their lives
in spectacular explosions called supernovas. Blown outward, bits of this
radioactive material mix with nebular gas and dust in the process of condensing
into stars and planets. When the solar system was forming, some of this material
hardened into rocks and later fell to Earth as meteorites.

The radioisotopes have long since vanished from meteorites found on Earth, but
they left their signatures in daughter species. By examining the abundances of
those daughter species, the researchers could calculate how far away the
supernova was, in both distance and time.

"The supernova was stunningly close; much closer to the sun than any star is
today," Fields said. "Our solar system was still in the process of forming when
the supernova occurred."

The massive star that exploded was formed in a group or cluster of stars with
perhaps hundreds, or even thousands, of low-mass stars like the sun, Fields
said. Because the stars were not gravitationally bound to one another, the sun's
siblings wandered away millennia ago.

Our solar system, rather than being the exception, could be the rule, the
astronomers said. Planetary system formation should be understood in this
context.

"We know that the majority of stars in our galaxy were born in star clusters,"
Looney said. "Now we also know that the newborn solar system not only arose in
such a cluster, but also survived the impact of an exploding star. This suggests
that planetary systems are impressively rugged, and may be common even in the
most tumultuous stellar nurseries."
Received on Thu 05 Oct 2006 02:02:18 AM PDT