[meteorite-list] Young Sun's Violent History Solves Meteorite Mystery (Herschel)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 1 Jul 2014 13:12:08 -0700 (PDT)
Message-ID: <201407012012.s61KC85Q013888_at_zagami.jpl.nasa.gov>

http://sci.esa.int/herschel/54252-young-suns-violent-history-solves-meteorite-mystery/

Young sun's violent history solves meteorite mystery
European Space Agency
01 July 2014

Astronomers using ESA's Herschel space observatory to probe the
turbulent beginnings of a Sun-like star have found evidence of
mighty stellar winds that could solve a puzzling meteorite mystery
in our own back yard.

In spite of their tranquil appearance in the night sky, stars are
scorching furnaces that spring to life through tumultuous
processes - and our 4.5 billion-year-old Sun is no exception. To
glimpse its harsh early days, astronomers gather clues not only in
the Solar System but also by studying young stars elsewhere in our
Galaxy.

Using Herschel to survey the chemical composition of regions where
stars are being born today, a team of astronomers has noticed that
one object in particular is different.

The unusual source is a prolific stellar nursery called OMC2 FIR4,
a clump of new stars embedded in a gaseous and dusty cloud near to
the famous Orion Nebula.

"To our great surprise, we found that the proportion of two
chemical species, one based on carbon and oxygen and the other on
nitrogen, is much smaller in this object than in any other
protostar we know," says Dr Cecilia Ceccarelli, of the Institute
de Planeologie et d'Astrophysique de Grenoble, France, who lead
the study with Dr Carsten Dominik of the University of Amsterdam
in the Netherlands.

In an extremely cold environment, the measured proportion could
arise by one of the two compounds freezing onto dust grains and
becoming undetectable. However, at the relatively 'high'
temperature of about -200??C found in star-forming regions like
OMC2 FIR4, this should not occur.

"The most likely cause in this environment is a violent wind of
very energetic particles, released by at least one of the
embryonic stars taking shape in this proto-stellar cocoon," Dr
Ceccarelli adds.

The most abundant molecule in star-forming clouds, hydrogen, can
be broken apart by cosmic rays, energetic particles that permeate
the entire Galaxy. The hydrogen ions then combine with other
elements that are present - albeit only in trace amounts - in
these clouds: carbon and oxygen, or nitrogen.

Normally, the nitrogen compound is also quickly destroyed,
yielding more hydrogen for the carbon and oxygen compound. As a
result, the latter is far more abundant in all known stellar
nurseries.

Strangely enough, though, this was not the case for OMC2 FIR4,
suggesting that an additional wind of energetic particles is
destroying both chemical species, keeping their abundances more
similar.

Astronomers think that a similarly violent wind of particles also
gusted through the early Solar System, and this discovery might
finally point to an explanation for the origin of a particular
chemical element seen in meteorites.

Meteorites are the remains of interplanetary debris that survived
the trip through our planet's atmosphere. These cosmic messengers
are one of the few tools we have to directly probe the elements in
our Solar System.

"Some elements detected in meteorites reveal that, long ago,
these rocks contained a form of beryllium: this is quite puzzling,
as we can't quite understand how it got there," explains Dr Dominik.

The formation of this isotope - beryllium-10 - in the Universe is
an intricate puzzle of its own. Astronomers know that it is not
produced in the interior of stars, like some other elements, nor
in the supernova explosion that happens at the end of a massive
star's life.

The majority of beryllium-10 was formed in collisions of very
energetic particles with heavier elements like oxygen. But since
this isotope decays very quickly into other elements, it must have
been produced just before it was incorporated in the rocks that
would later appear on Earth as meteorites.

In order to trigger these reactions and produce an amount of
beryllium matching that recorded in meteorites, our own Sun must
have blown a violent wind in its youth.

These new observations of OMC2 FIR4 give a very strong hint that
it is possible for a young star to do this.

"Observing star-forming regions with Herschel not only provides
us with a view on what happens beyond our cosmic neighbourhood,
but it's also a crucial way to piece together the past of our own
Sun and Solar System," says Goran Pilbratt, ESA's Herschel
project scientist.


More information

"Herschel finds evidence for stellar wind particles in a
protostellar envelope: is this what happened to the young Sun?"
by C. Ceccarelli et al. is published in the Astrophysical Journal
Letters, July 2014.

The study is based on observations performed with the Heterodyne
Instrument for the Far-Infrared (HIFI) on Herschel, as part of the
Herschel Guaranteed Time Key Programme Chemical HErschel Surveys
of Star forming regions (CHESS).


For further information, please contact:

Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email: markus.bauer at esa.int

Cecilia Ceccarelli
Institute de Planetologie et d'Astrophysique de Grenoble
Grenoble, France
Tel: +33 476 514 201
Email: Cecilia.Ceccarelli at obs.ujf-grenoble.fr

Carsten Dominik
Astronomical Institute "Anton Pannekoek", University of Amsterdam
Amsterdam, The Netherlands
Tel: +31 6 43 710 210
Email: dominik at uva.nl

Goran Pilbratt
Herschel Project Scientist
Tel: +31 71 565 3621
Email: gpilbratt at cosmos.esa.int
Received on Tue 01 Jul 2014 04:12:08 PM PDT