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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 559495.0, MPI für Astronomie / Publikationen_mpia
A ground-based near-infrared emission spectrum of the exoplanet HD189733b
Authors:Swain, Mark R.; Deroo, Pieter; Griffith, Caitlin A.; Tinetti, Giovanna; Thatte, Azam; Vasisht, Gautam; Chen, Pin; Bouwman, Jeroen; Crossfield, Ian J.; Angerhausen, Daniel; Afonso, Cristina; Henning, Thomas
Date of Publication (YYYY-MM-DD):2010
Title of Journal:Nature
Issue / Number:7281
Start Page:637
End Page:639
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Detection of molecules using infrared spectroscopy probes the conditions and compositions of exoplanet atmospheres. Water (H2O), methane (CH4), carbon dioxide (CO2), and carbon monoxide (CO) have been detected in two hot Jupiters. These previous results relied on space-based telescopes that do not provide spectroscopic capability in the 2.4-5.2μm spectral region. Here we report ground-based observations of the dayside emission spectrum for HD189733b between 2.0-2.4μm and 3.1-4.1μm, where we find a bright emission feature. Where overlap with space-based instruments exists, our results are in excellent agreement with previous measurements. A feature at ~3.25μm is unexpected and difficult to explain with models that assume local thermodynamic equilibrium (LTE) conditions at the 1bar to 1×10-6bar pressures typically sampled by infrared measurements. The most likely explanation for this feature is that it arises from non-LTE emission from CH4, similar to what is seen in the atmospheres of planets in our own Solar System. These results suggest that non-LTE effects may need to be considered when interpreting measurements of strongly irradiated exoplanets.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2010Natur.463..637S [ID No:1]
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