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The presence of methane in the atmosphere of an extrasolar planet

Show simple item record Swain, Mark R. Vasisht, Gautam Tinetti, Giovanna 2008-07-28T22:48:06Z 2008-07-28T22:48:06Z 2008-03-20
dc.identifier.citation Nature 452, 329-331 (20 March 2008), doi:10.1038/nature06823 en_US
dc.identifier.clearanceno 08-1099
dc.description.abstract Molecules present in the atmospheres of extrasolar planets are expected to influence strongly the balance of atmospheric radiation, to trace dynamical and chemical processes, and to indicate the presence of disequilibrium effects. As molecules have the potential to reveal atmospheric conditions and chemistry, searching for them is a high priority. The rotational–vibrational transition bands of water, carbon monoxide and methane are anticipated to be the primary sources of non-continuum opacity in hot-Jupiter planets. As these bands can overlap in wavelength, and the corresponding signatures from them are weak, decisive identification requires precision infrared spectroscopy. Here we report a near-infrared transmission spectrum of the planet HD 189733b that shows the presence of methane. Additionally, a resolved water vapour band at 1.9 µm confirms the recent claim4 of water in this object. On thermochemical grounds, carbon monoxide is expected to be abundant in the upper atmosphere of hot-Jupiter planets, but is not identifiable here; herefore the detection of methane rather than carbon monoxide in such a hot planet could signal the presence of a horizontal chemical gradient away from the permanent dayside, or it may imply an ill-understood photochemical mechanism that leads to an enhancement of methane. en_US
dc.description.sponsorship NASA/JPL en_US
dc.language.iso en_US en_US
dc.publisher Nature Publishing Group en_US
dc.subject methane en_US
dc.subject atmospheric radiation en_US
dc.subject extrasolar planets
dc.title The presence of methane in the atmosphere of an extrasolar planet en_US
dc.type Article en_US

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