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Title: Transmission spectroscopy of the hot Jupiter WASP-12b from 0.7 to 5 μm

Since the first report of a potentially non-solar carbon-to-oxygen ratio (C/O) in its dayside atmosphere, the highly irradiated exoplanet WASP-12b has been under intense scrutiny and the subject of many follow-up observations. Additionally, the recent discovery of stellar binary companions ∼1'' from WASP-12 has obfuscated interpretation of the observational data. Here we present new ground-based multi-object transmission-spectroscopy observations of WASP-12b that we acquired over two consecutive nights in the red optical with Gemini-N/GMOS. After correcting for the influence of WASP-12's stellar companions, we find that these data rule out a cloud-free H{sub 2} atmosphere with no additional opacity sources. We detect features in the transmission spectrum that may be attributed to metal oxides (such as TiO and VO) for an O-rich atmosphere or to metal hydrides (such as TiH) for a C-rich atmosphere. We also reanalyzed NIR transit-spectroscopy observations of WASP-12b from HST/WFC3 and broadband transit photometry from Warm Spitzer. We attribute the broad spectral features in the WFC3 data to either H{sub 2}O or CH{sub 4} and HCN for an O-rich or C-rich atmosphere, respectively. The Spitzer data suggest shallower transit depths than the models predict at infrared wavelengths, albeit at low statistical significance. A multi-instrument, broad-wavelength analysis ofmore » WASP-12b suggests that the transmission spectrum is well approximated by a simple Rayleigh scattering model with a planet terminator temperature of 1870 ± 130 K. We conclude that additional high-precision data and isolated spectroscopic measurements of the companion stars are required to place definitive constraints on the composition of WASP-12b's atmosphere.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
  2. Division of Geological and Planetary Sciences, California Institute of Technology, MC 170-25 1200, East California Boulevard, Pasadena, CA 91125 (United States)
  3. Department of Physics and Department of Astronomy, Yale University, P.O. Box 208120, New Haven, CT 06520 (United States)
  4. National Optical Astronomy Observatory (NOAO), Tucson, AZ 85719 (United States)
  5. Centre de Recherche Astrophysique de Lyon, UMR 5574, CNRS, Université de Lyon, École Normale Supérieure de Lyon, 46 Allée d'Italie, F-69364 Lyon Cedex 07 (France)
Publication Date:
OSTI Identifier:
22340214
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 147; Journal Issue: 6; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATMOSPHERES; CARBON; HYDRIDES; HYDROCYANIC ACID; HYDROGEN; IRRADIATION; JUPITER PLANET; METALS; METHANE; OPACITY; OXYGEN; PHOTOMETRY; RAYLEIGH SCATTERING; SPECTRA; SPECTROSCOPY; STARS; TITANIUM OXIDES; TRANSMISSION; VANADIUM OXIDES; WATER