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Water, Methane, and Carbon Dioxide Present in the Dayside Spectrum of the Exoplanet HD 209458b

Swain, M. R. and Tinetti, G. and Vasisht, G. and Deroo, P. and Griffith, C. and Bouwman, J. and Chen, Pin and Yung, Y. and Burrows, A. S. and Brown, L. R. and Matthews, J. and Rowe, J. F. and Kuschnig, R. and Angerhausen, D. (2009) Water, Methane, and Carbon Dioxide Present in the Dayside Spectrum of the Exoplanet HD 209458b. Astrophysical Journal, 704 (2). pp. 1616-1621. ISSN 0004-637X.

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Using the NICMOS instrument on the Hubble Space Telescope, we have measured the dayside spectrum of HD 209458b between 1.5 and 2.5 μm. The emergent spectrum is dominated by features due to the presence of methane (CH_4) and water vapor (H_2O), with smaller contributions from carbon dioxide (CO_2). Combining this near-infrared spectrum with existing mid-infrared measurements shows the existence of a temperature inversion and confirms the interpretation of previous photometry measurements. We find a family of plausible solutions for the molecular abundance and detailed temperature profile. Observationally resolving the ambiguity between abundance and temperature requires either (1) improved wavelength coverage or spectral resolution of the dayside emission spectrum or (2) a transmission spectrum where abundance determinations are less sensitive to the temperature structure.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Swain, M. R.0000-0002-0919-4468
Vasisht, G.0000-0002-1871-6264
Yung, Y.0000-0002-4263-2562
Burrows, A. S.0000-0002-3099-5024
Rowe, J. F.0000-0002-5904-1865
Additional Information:© 2009 The American Astronomical Society. Received 2009 April 28; accepted 2009 August 21; published 2009 October 6. We appreciate the Director’s Time Award for these observations, and we thank Tommy Wiklind, Beth Padillo, and other members of the Space Telescope Science Institute staff for assistance in planning the observations. We also thank Jonathan Tennyson and Bob Barber for help with the water line list. G.T. was supported by the Royal Society. A portion of the research described in this paper was carried out at the Jet Propulsion Laboratory, under a contact with the National Aeronautics and Space Administration.
Funding AgencyGrant Number
Subject Keywords:planetary systems; techniques: spectroscopic
Issue or Number:2
Record Number:CaltechAUTHORS:20091021-113138246
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Official Citation:Water, Methane, and Carbon Dioxide Present in the Dayside Spectrum of the Exoplanet HD 209458b M. R. Swain, G. Tinetti, G. Vasisht, P. Deroo, C. Griffith, J. Bouwman, Pin Chen, Y. Yung, A. Burrows, L. R. Brown, J. Matthews, J. F. Rowe, R. Kuschnig, and D. Angerhausen 2009 ApJ 704 1616-1621 doi: 10.1088/0004-637X/704/2/1616
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16427
Deposited By: Tony Diaz
Deposited On:29 Oct 2009 19:44
Last Modified:09 Mar 2020 13:19

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