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Transmission Spectroscopy of the Hot Jupiter WASP-12b from 0.7 to 5 μm

Stevenson, Kevin B. and Bean, Jacob L. and Seifahrt, Andreas and Désert, Jean-Michel and Madhusudhan, Nikku and Bergmann, Marcel and Kreidberg, Laura and Homeier, Derek (2014) Transmission Spectroscopy of the Hot Jupiter WASP-12b from 0.7 to 5 μm. Astronomical Journal, 147 (6). Art. No. 161. ISSN 0004-6256.

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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_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_2O or CH_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 of 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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Stevenson, Kevin B.0000-0002-7352-7941
Bean, Jacob L.0000-0003-4733-6532
Désert, Jean-Michel0000-0002-0875-8401
Madhusudhan, Nikku0000-0002-4869-000X
Kreidberg, Laura0000-0003-0514-1147
Alternate Title:Transmission Spectroscopy of the Hot-Jupiter WASP-12b from 0.7 to 5 microns
Additional Information:© 2014 American Astronomical Society. Received 2013 May 7; accepted 2014 April 14; published 2014 May 14. We thank Carlo Graziani for providing comments related to the Divide-White technique and also Jonathan Tennyson and Christian Hill for helpful discussions. We thank contributors to SciPy, Matplotlib, and the Python Programming Language, the free and open-source community, the NASA Astrophysics Data System, and the JPL Solar System Dynamics group for software and services. This research made use of Tiny Tim/Spitzer, developed by John Krist for the Spitzer Science Center. The Center is managed by the California Institute of Technology under a contract with NASA. Funding for this work has been provided by NASA grant NNX13AJ16G. J.L.B. acknowledges support from the Alfred P. Sloan Foundation. J.-M.D. acknowledges funding from NASA through the Sagan Exoplanet Fellowship program administered by the NASA Exoplanet Science Institute (NExScI). N.M. acknowledges support from the Yale Center for Astronomy and Astrophysics (YCAA) through the YCAA postdoctoral prize fellowship. L.K. acknowledges support from the National Science Foundation Graduate Research Fellowship Program. D.H. acknowledges support from the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013 Grant Agreement no. 247060). This work is based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovaciόn Productiva (Argentina).
Funding AgencyGrant Number
Alfred P. Sloan FoundationUNSPECIFIED
NASA Exoplanet Science InstituteUNSPECIFIED
Yale Center for Astronomy and AstrophysicsUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
European Research Council (ERC)247060
Subject Keywords: planetary systems; stars: individual (WASP-12); techniques: spectroscopic
Issue or Number:6
Record Number:CaltechAUTHORS:20140620-092701545
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Official Citation:Transmission Spectroscopy of the Hot Jupiter WASP-12b from 0.7 to 5 μm Kevin B. Stevenson et al. 2014 The Astronomical Journal 147 161
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46391
Deposited By: Ruth Sustaita
Deposited On:20 Jun 2014 17:12
Last Modified:06 Nov 2019 18:32

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