Astronomers Detect First Organic Molecule on an Exoplanet

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Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
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Ray Villard 410-338-4514
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.edu

NEWS RELEASE: 2008-046 March 19, 2008

Astronomers Detect First Organic Molecule on an Exoplanet

A team of astronomers led by Mark Swain of NASA's Jet Propulsion Laboratory, Pasadena,
Calif., has made the first detection ever of an organic molecule in the atmosphere of a Jupiter-
sized planet orbiting another star. The breakthrough, made with NASA's Hubble Space
Telescope, is an important step in eventually identifying signs of life on a planet outside our
solar system.

The molecule found by Hubble is methane, which under the right circumstances can play a key
role in prebiotic chemistry - the chemical reactions considered necessary to form life as we know
it.

This discovery proves that Hubble and upcoming space missions, such as NASA's James Webb
Space Telescope, can detect organic molecules on planets around other stars by using
spectroscopy, which splits light into its components to reveal the "fingerprints" of various
chemicals.

"This is a crucial stepping stone to eventually characterizing prebiotic molecules on planets
where life could exist," said Swain, lead author of a paper appearing in the March 20 issue of
Nature.

The discovery comes after extensive observations made in May 2007 with Hubble's Near
Infrared Camera and Multi-Object Spectrometer. It also confirms the existence of water
molecules in the planet's atmosphere, a discovery made originally by NASA's Spitzer Space
Telescope in 2007. "With this observation there is no question whether there is water or not -
water is present," said Swain.

The planet now known to have methane and water is located 63 light-years away in the
constellation Vulpecula. Called HD 189733b, the planet is so massive and so hot it is considered
an unlikely host for life. HD 189733b, dubbed a "hot Jupiter," is so close to its parent star it takes
just over two days to complete an orbit. These objects are the size of Jupiter but orbit closer to
their stars than the tiny innermost planet Mercury in our solar system. HD 189733b's atmosphere
swelters at 1700 degrees Fahrenheit, about the same temperature as the melting point of silver.

Though the star-hugger planet is too hot for life as we know it, "this observation is proof that
spectroscopy can eventually be done on a cooler and potentially habitable Earth-sized planet
orbiting a dimmer red dwarf-type star," Swain said. The ultimate goal of studies like these is to
identify prebiotic molecules in the atmospheres of planets in the "habitable zones" around other
stars, where temperatures are right for water to remain liquid rather than freeze or evaporate
away.

The observations were made as the planet HD 189733b passed in front of its parent star in what
astronomers call a transit. As the light from the star passed briefly through the atmosphere along
the edge of the planet, the gases in the atmosphere imprinted their unique signatures on the
starlight from the star HD 189733.

The astronomers were surprised to find that the planet has more methane than predicted by
conventional models for "hot Jupiters." "This indicates we don't really understand exoplanet
atmospheres yet," said Swain.

"These measurements are an important step to our ultimate goal of determining the conditions,
such as temperature, pressure, winds, clouds, etc., and the chemistry on planets where life could
exist. Infrared spectroscopy is really the key to these studies because it is best matched to
detecting molecules," said Swain.

More information on the discovery and artist's concepts are online at:
http://hubblesite.org/news/2008/11 . Swain's co-authors on the paper include Gautam Vasisht
of JPL and Giovanna Tinetti of University College, London.

The Hubble Space Telescope is a project of international cooperation between NASA and the
European Space Agency and is managed by NASA's Goddard Space Flight Center in Greenbelt,
Md. The Space Telescope Science Institute conducts Hubble science operations. The institute is
operated for NASA by the Association of Universities for Research in Astronomy, Inc.,
Washington, DC. Scheduled for launch in 2013, the James Webb Space Telescope is an
international collaboration between NASA, ESA, and the Canadian Space Agency (CSA). GSFC
is managing the development effort. The prime contractor is Northrop Grumman Space
Technologies. STScI will operate JWST after launch.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate,
Washington. Science operations are conducted at the Spitzer Science Center at the California
Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Previous Spitzer
discoveries regarding HD 189733b from Swain and others can be read at

http://www.spitzer.caltech.edu/Media/releases/ssc2007-04/release.shtml .

Read a profile about astronomer Mark Swain at

http://www.jpl.nasa.gov/news/features.cfm?feature=1641

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