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" f...

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Bibliographic Details
Published in:The Astronomical journal Vol. 147; no. 6; pp. 161 - 18
Main Authors: Stevenson, Kevin B., Bean, Jacob L., Seifahrt, Andreas, Désert, Jean-Michel, Madhusudhan, Nikku, Bergmann, Marcel, Kreidberg, Laura, Homeier, Derek
Format: Journal Article
Language:English
Published: United States 01.06.2014
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ATMOSPHERES
CARBON
Companion stars
Extrasolar planets
HYDRIDES
HYDROCYANIC ACID
HYDROGEN
IRRADIATION
JUPITER PLANET
METALS
METHANE
OPACITY
OXYGEN
PHOTOMETRY
RAYLEIGH SCATTERING
SPECTRA
SPECTROSCOPY
STARS
Stellar atmospheres
Temperature
TITANIUM OXIDES
Transit
TRANSMISSION
VANADIUM OXIDES
WATER
ISSN:0004-6256, 1538-3881, 1538-3881
Online Access:Get full text
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Summary: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" fromWASP-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 H2 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 theWFC3 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 ofWASP-12b suggests that the transmission spectrum is well approximated by a simple Rayleigh scattering model with a planet terminator temperature of 1870 + or - 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.
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ISSN:0004-6256
1538-3881
1538-3881
DOI:10.1088/0004-6256/147/6/161