[meteorite-list] Scientists' Stardust Analysis Brings Nucleosynthesis Full Circle

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:24 2004
Message-ID: <200402191657.IAA21532_at_zagami.jpl.nasa.gov>

http://chronicle.uchicago.edu/040219/stardust.shtml

Scientists' stardust analysis brings nucleosynthesis full circle
By Catherine Foster, Argonne National Laboratory
The University of Chicago Chronicle
Vol 23 No 10.
February 19, 2004

Researchers at Argonne National Laboratory have reached
for the stars - and seen what is inside.

Argonne scientists, in collaboration with
University researchers and colleagues at Washington
University and the Universita di Torino in Italy,
examined stardust from a meteorite and found
remnants of now-extinct technetium atoms made in
stars long ago.

The stardust grains are tiny bits of stars that
lived and died before the solar system formed. Each
grain is many times smaller than the width of a
human hair and carries a chemical record of nuclear
reactions in its parent star.

Fifty years ago, famed scientist P.W. Merrill
observed the signature of live technetium - an
element that has no stable isotopes - in the
starlight from certain types of stars, thereby
proving the then-controversial theory that stars
make atoms via a process called nucleosynthesis.
The researchers' discovery that their stardust
grains once harbored live technetium brings the
science of nucleosynthesis full circle.

"Finding traces of technetium decay products in
stardust provides a very precise confirmation of
the theories of how atoms are made inside stars,"
said Michael Savina, Argonne scientist and lead
author of the research, which was published in the
Friday, Jan. 30 issue of Science. "The fact that we
can both predict and measure very tiny effects in
the chemistry of these grains gives us a lot of
confidence in our models of how stars work."

Authors of the report, in addition to Savina, are
Michael Pellin and C. Emil Tripa of Argonne
National Laboratory; Andrew Davis and Roy Lewis,
Senior Scientists in the University's Enrico Fermi
Institute; Sachiko Amari of Washington University
in St. Louis; and Roberto Gallino of the Universita
di Torino.

The work was made possible by a specialized
instrument at Argonne called CHARISMA, the only
instrument of its type in the world.

"CHARISMA is designed to analyze very tiny
samples - the kind where you can't afford to
waste atoms because there are so few of them to
work with," Savina said.

The Department of Energy Office of Science and NASA
are funding the current upgrade of CHARISMA in
anticipation of solar wind samples from the Genesis
mission. Scientists believe the solar
wind - single atoms and electrically charged
particles from the sun - has not changed since
the sun was born.

The research group at Argonne will be among the
scientists to analyze the samples in an effort to
better understand how the planets formed. Current
measurements of the sun's composition are not
precise enough to answer key questions about events
in the early solar system. The researchers also are
preparing to analyze samples from the Stardust
mission, which recently captured dust grains from a
comet's tail and will bring them back to Earth in
2006.

The nation's first national laboratory, Argonne
National Laboratory conducts basic and applied
scientific research across a wide spectrum of
disciplines, ranging from high-energy physics to
climatology and biotechnology. The University
operates Argonne as part of the U.S. Department of
Energy's national laboratory system, and has since
Argonne's creation in 1946.
Received on Thu 19 Feb 2004 11:57:20 AM PST