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The 3.6-8.0 μm Broadband Emission Spectrum of HD 209458b: Evidence for an Atmospheric Temperature Inversion

Knutson, Heather A. and Charbonneau, David and Allen, Lori E. and Burrows, Adam and Megeath, S. Thomas (2008) The 3.6-8.0 μm Broadband Emission Spectrum of HD 209458b: Evidence for an Atmospheric Temperature Inversion. Astrophysical Journal, 673 (1). pp. 526-531. ISSN 0004-637X. doi:10.1086/523894.

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We estimate the strength of the bandpass-integrated thermal emission from the extrasolar planet HD 209458b at 3.6, 4.5, 5.8, and 8.0 μm using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We observe a single secondary eclipse simultaneously in all four bandpasses and find relative eclipse depths of 0.00094 ± 0.00009, 0.00213 ± 0.00015, 0.00301 ± 0.00043, and 0.00240 ± 0.00026, respectively. These eclipse depths reveal that the shape of the inferred emission spectrum for the planet differs significantly from the predictions of standard atmosphere models; instead, the most plausible explanation would require the presence of an inversion layer high in the atmosphere leading to significant water emission in the 4.5 and 5.8 μm bandpasses. This is the first clear indication of such a temperature inversion in the atmosphere of a hot Jupiter, as previous observations of other planets appeared to be in reasonably good agreement with the predictions of models without such an inversion layer.

Item Type:Article
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URLURL TypeDescription Paper
Knutson, Heather A.0000-0002-0822-3095
Charbonneau, David0000-0002-9003-484X
Burrows, Adam0000-0002-3099-5024
Megeath, S. Thomas0000-0001-7629-3573
Additional Information:© 2008 American Astronomical Society. Received 2007 July 31; accepted 2007 September 24. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. H. A. K. was supported by a National Science Foundation Graduate Research Fellowship.A. B.would like to acknowledge support from NASA under grants NNG04GL22G and NNX07AG80G and through the NASA Astrobiology Institute under cooperative agreement CAN-02-OSS-02 issued through the Office of Space Science. We would also like to thank J. Matthews for sharing MOST results in advance of publication.
Group:UNSPECIFIED, Division of Geological and Planetary Sciences
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NSF Graduate Research FellowshipUNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20130129-104056356
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Official Citation:The 3.6-8.0 μm Broadband Emission Spectrum of HD 209458b: Evidence for an Atmospheric Temperature Inversion Heather A. Knutson et al. 2008 ApJ 673 526
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36644
Deposited By: Ruth Sustaita
Deposited On:29 Jan 2013 19:00
Last Modified:09 Nov 2021 23:23

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