Violent wind gusting around protostar in Orion - (Hi-Res JPG)
Orion A, a star-forming nebula lying about 1500 light-years from
Earth, as viewed by ESA’s Herschel space observatory. Orion A is located
within the ‘sword of Orion’ – below the three main stars that form the
belt of the Orion constellation.
Embedded in the gaseous and dusty
environment of this molecular cloud is the prolific stellar nursery
called OMC2 FIR4 (highlighted with a red circle).
Astronomers
studying OMC2 FIR4 with Herschel have discovered that at least one of
the embryo stars that are taking shape in this protostellar cocoon is
gusting a powerful wind of very energetic particles.
The inset
shows an illustration of the wind blown by this newborn star. When the
energetic particles hit the surrounding material, they may collide with
atoms that are present in the star's environment, break them apart and
produce new elements.
Our Sun likely gusted a similar wind of
particles in its early days; this could explain the origin of a puzzling
isotope of beryllium, whose traces are found in meteorites. Copyright: Herschel image:
ESA/Herschel/Ph. André, D. Polychroni, A. Roy, V. Könyves, N. Schneider
for the Gould Belt survey Key Programme; inset and layout: ESA/ATG
medialab
An illustration of the wind blown by a newborn star. When the
energetic particles hit the surrounding material, they may collide with
atoms that are present in the star's environment, break them apart and
produce new elements. Copyright: ESA/ATG medialab
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 Planétologie 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 Göran Pilbratt, ESA’s Herschel project scientist.
More information
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@esa.int
Cecilia Ceccarelli
Institute de Planétologie et d’Astrophysique de Grenoble
Grenoble, France
Tel: +33 476 514 201
Email: Cecilia.Ceccarelli@obs.ujf-grenoble.fr
Carsten Dominik
Astronomical Institute “Anton Pannekoek”, University of Amsterdam
Amsterdam, The Netherlands
Tel: +31 6 43 710 210
Email: dominik@uva.nl
Göran Pilbratt
Herschel Project Scientist
Tel: +31 71 565 3621
Email: gpilbratt@cosmos.esa.int
“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@esa.int
Cecilia Ceccarelli
Institute de Planétologie et d’Astrophysique de Grenoble
Grenoble, France
Tel: +33 476 514 201
Email: Cecilia.Ceccarelli@obs.ujf-grenoble.fr
Carsten Dominik
Astronomical Institute “Anton Pannekoek”, University of Amsterdam
Amsterdam, The Netherlands
Tel: +31 6 43 710 210
Email: dominik@uva.nl
Göran Pilbratt
Herschel Project Scientist
Tel: +31 71 565 3621
Email: gpilbratt@cosmos.esa.int
Source: ESA