ALMA and Rosetta Detect Freon-40 in Space
ROSINA on Rosetta finds Freon-40 at Comet 67P/Churyumov–Gerasimenko
IRAS 16293-2422 in the constellation of Ophiuchus
The Rho Ophiuchi star formation region in the constellation of Ophiuchus
ALMA and Rosetta Detect Freon-40 in Space
Videos
Zooming in on the Rho Ophiuchi star formation region
Dashing Hopes that Molecule May be Marker of Life
Observations made with the Atacama Large
Millimeter/submillimeter Array (ALMA) and ESA’s Rosetta mission, have
revealed the presence of the organohalogen Freon-40 in gas around both
an infant star and a comet. Organohalogens are formed by organic
processes on Earth, but this is the first ever detection of them in
interstellar space. This discovery suggests that organohalogens may not
be as good markers of life as had been hoped, but that they may be
significant components of the material from which planets form. This
result, which appears in the journal Nature Astronomy, underscores the
challenge of finding molecules that could indicate the presence of life
beyond Earth.
Using data captured by ALMA in Chile and from the ROSINA instrument on ESA’s Rosetta mission, a team of astronomers has found faint traces of the chemical compound Freon-40 (CH3Cl), also known as methyl chloride and chloromethane, around both the infant star system IRAS 16293-2422 [1], about 400 light-years away, and the famous comet 67P/Churyumov-Gerasimenko (67P/C-G) in our own Solar System. The new ALMA observation is the first detection ever of a stable organohalogen in interstellar space [2].
Organohalogens consist of halogens, such as chlorine and
fluorine, bonded with carbon and sometimes other elements. On Earth,
these compounds are created by some biological processes — in organisms
ranging from humans to fungi — as well as by industrial processes such
as the production of dyes and medical drugs [3].
This new discovery of one of these compounds, Freon-40, in
places that must predate the origin of life, can be seen as a
disappointment, as earlier research had suggested that these molecules
could indicate the presence of life.
“Finding the organohalogen Freon-40 near these young, Sun-like stars was surprising,”
said Edith Fayolle, a researcher with the Harvard-Smithsonian Center
for Astrophysics in Cambridge, Massachusetts in the USA, and lead author
of the new paper. “We simply didn't predict its formation and were
surprised to find it in such significant concentrations. It’s clear now
that these molecules form readily in stellar nurseries, providing
insights into the chemical evolution of planetary systems, including our
own.”
Exoplanet research has gone beyond the point of finding planets — more than 3000 exoplanets are now known
— to looking for chemical markers that might indicate the potential
presence of life. A vital step is determining which molecules could
indicate life, but establishing reliable markers remains a tricky
process.
“ALMA’s discovery of organohalogens in the interstellar
medium also tells us something about the starting conditions for
organic chemistry on planets. Such chemistry is an important step toward
the origins of life,” adds Karin Öberg, a co-author on the study. “Based
on our discovery, organohalogens are likely to be a constituent of the
so-called ‘primordial soup’, both on the young Earth and on nascent
rocky exoplanets.”
This suggests that astronomers may have had things around
the wrong way; rather than indicating the presence of existing life,
organohalogens may be an important element in the little-understood
chemistry involved in the origin of life.
Co-author Jes Jørgensen from the Niels Bohr Institute at University of Copenhagen adds: "This
result shows the power of ALMA to detect molecules of astrobiological
interest toward young stars on scales where planets may be forming.
Using ALMA we have previously found precursors to sugars and
amino acids around different stars. The additional discovery of Freon-40
around Comet 67P/C-G strengthens the links between the pre-biological
chemistry of distant protostars and our own Solar System."
The astronomers also compared the relative amounts of
Freon-40 that contain different isotopes of chlorine in the infant star
system and the comet — and found similar abundances. This supports the
idea that a young planetary system can inherit the chemical composition
of its parent star-forming cloud and opens up the possibility that
organohalogens could arrive on planets in young systems during planet
formation or via comet impacts.
“Our results shows that we still have more to learn about the formation of organohalogens,” concludes Fayolle. “Additional searches for organohalogens around other protostars and comets need to be undertaken to help find the answer.”
Notes
[1] This protostar is a binary star system surrounded by a molecular cloud in the Rho Ophiuchi star-forming region, which makes it an excellent target for ALMA’s millimetre/submillimetre view.
[2] The data used were from the ALMA Protostellar Interferometric Line Survey (PILS).
The aim of this survey is to chart the chemical complexity of IRAS
16293-2422 by imaging the full wavelength range covered by ALMA in the
0.8-millimetre atmospheric window on very small scales, equivalent to
the size of the Solar System.
The species CF+, which could be considered as an organohalogen, had already been detected, but is not stable.
[3] Freons were widely used
as a refrigerants (hence the name) but are now banned as they have a
destructive effect on the Earth’s protective ozone layer.
More Information
This research was presented in a paper “Protostellar and Cometary Detections of Organohalogens” by E. Fayolle et al., to appear in Nature Astronomy on 2 October 2017.
This research was presented in a paper “Protostellar and Cometary Detections of Organohalogens” by E. Fayolle et al., to appear in Nature Astronomy on 2 October 2017.
The team is composed of Edith C. Fayolle
(Harvard-Smithsonian Center for Astrophysics, USA), Karin I. Öberg
(Harvard-Smithsonian Center for Astrophysics, USA), Jes K. Jørgensen
(University of Copenhagen, Denmark), Kathrin Altwegg (University of
Bern, Switzerland), Hannah Calcutt (University of Copenhagen, Denmark),
Holger S. P. Müller (Universität zu Köln, Germany), Martin Rubin
(University of Bern, Switzerland), Matthijs H. D. van der Wiel (The
Netherlands Institute for Radio Astronomy, The Netherlands), Per
Bjerkeli (Onsala Space Observatory, Sweden), Tyler L. Bourke (Jodrell
Bank Observatory, UK), Audrey Coutens (University College London, UK),
Ewine F. van Dishoeck (Leiden University, The Netherlands;
Max-Planck-Institut für extraterrestrische Physik, Germany), Maria N.
Drozdovskaya (University of Bern, Switzerland), Robin T. Garrod
(University of Virginia, USA), Niels F. W. Ligterink (Leiden University,
The Netherlands), Magnus V. Persson (Onsala Space Observatory, Sweden),
Susanne F. Wampfler (University of Bern, Switzerland) and the ROSINA
team.
The Atacama Large Millimeter/submillimeter Array (ALMA), an
international astronomy facility, is a partnership of ESO, the U.S.
National Science Foundation (NSF) and the National Institutes of Natural
Sciences (NINS) of Japan in cooperation with the Republic of Chile.
ALMA is funded by ESO on behalf of its Member States, by NSF in
cooperation with the National Research Council of Canada (NRC) and the
National Science Council of Taiwan (NSC) and by NINS in cooperation with
the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space
Science Institute (KASI).
ALMA construction and operations are led by ESO on behalf
of its Member States; by the National Radio Astronomy Observatory
(NRAO), managed by Associated Universities, Inc. (AUI), on behalf of
North America; and by the National Astronomical Observatory of Japan
(NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides
the unified leadership and management of the construction,
commissioning and operation of ALMA.
ESO is the foremost intergovernmental astronomy
organisation in Europe and the world’s most productive ground-based
astronomical observatory by far. It is supported by 16 countries:
Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland,
Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden,
Switzerland and the United Kingdom, along with the host state of Chile.
ESO carries out an ambitious programme focused on the design,
construction and operation of powerful ground-based observing facilities
enabling astronomers to make important scientific discoveries. ESO also
plays a leading role in promoting and organising cooperation in
astronomical research. ESO operates three unique world-class observing
sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO
operates the Very Large Telescope and its world-leading Very Large
Telescope Interferometer as well as two survey telescopes, VISTA working
in the infrared and the visible-light VLT Survey Telescope. ESO is also
a major partner in two facilities on Chajnantor, APEX and ALMA, the
largest astronomical project in existence. And on Cerro Armazones, close
to Paranal, ESO is building the 39-metre Extremely Large Telescope, the
ELT, which will become “the world’s biggest eye on the sky”.
Links
- Research paper in Nature Astronomy
- Earlier results on this star from ALMA: methyl isocyanate and sugars
- Photos of ALMA
Contacts
Edith Fayolle
Harvard-Smithsonian Center for Astrophysics
Cambridge, Massachusetts, USA
Email: fayolle@cfa.harvard.edu
Jes K. Jørgensen
Niels Bohr Institute, University of Copenhagen
Copenhagen, Denmark
Tel: +45 4250 9970
Email: jeskj@nbi.dk
Ewine van Dishoeck
Leiden Observatory
Leiden, Netherlands
Tel: +31 71 5275814
Email: ewine@strw.leidenuniv.nl
Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Source: ESO/News
