WATER, METHANE, AND CARBON DIOXIDE PRESENT IN THE DAYSIDE SPECTRUM OF THE EXOPLANET HD 209458b

2009/08/27 by M. Swain, Mark G. Swain, G. Tinetti +20 · 3 citations
Chemistry · Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Carbon dioxide #Chemistry #Exoplanet #Infrared #Methane #Physics #Planet #Spectral line #Spectral resolution #Stellar, planetary, and galactic studies #astro-ph.EP #astro-ph.SR

paper · pdf · doi:10.1088/0004-637x/704/2/1616

14 pages, 6 figures, accepted for publication in ApJ

arxiv created 2009/08/27 · openalex publication_date 2009/10/06 · arxiv updated 2015/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

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 2 O), 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.

Citations

• TheMOSTAsteroseismology Mission: Ultraprecise Photometry from Space
• Atmospheric Circulation of Hot Jupiters: Three‐dimensional Circulation Models of HD 209458b and HD 189733b with Simplified Forcing
• Detection of an Extrasolar Planet Atmosphere
• Infrared Transmission Spectra for Extrasolar Giant Planets
• The Mid‐Infrared Spectrum of the Transiting Exoplanet HD 209458b

Cited by

• Toward Direct Detection of Hot Jupiters with Precision Closure Phase: Calibration Studies and First Results from the CHARA Array
• THE 4.5 μm FULL-ORBIT PHASE CURVE OF THE HOT JUPITER HD 209458b
• A chemical model for the atmosphere of hot Jupiters

Related

• Molecular Signatures in the Near Infrared Dayside Spectrum of HD 189733b
• Methane present in an extrasolar planet atmosphere
• The watery atmosphere of HD~209458~b revealed by joint K- and L-band high-resolution spectroscopy
• Optimal Estimation Retrievals of the Atmospheric Structure and Composition of HD 189733b from Secondary Eclipse Spectroscopy
• Four HD 209458 b transits through CRIRES+: Detection of H₂O and non-detections of C₂H₂, CH₄, and HCN