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Title: Exoplanet transit spectroscopy using WFC3: WASP-12 b, WASP-17 b, and WASP-19 b

We report an analysis of transit spectroscopy of the extrasolar planets WASP-12 b, WASP-17 b, and WASP-19 b using the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). We analyze the data for a single transit for each planet using a strategy similar, in certain aspects, to the techniques used by Berta et al., but we extend their methodology to allow us to correct for channel- or wavelength-dependent instrumental effects by utilizing the band-integrated time series and measurements of the drift of the spectrum on the detector over time. We achieve almost photon-limited results for individual spectral bins, but the uncertainties in the transit depth for the band-integrated data are exacerbated by the uneven sampling of the light curve imposed by the orbital phasing of HST's observations. Our final transit spectra for all three objects are consistent with the presence of a broad absorption feature at 1.4 μm most likely due to water. However, the amplitude of the absorption is less than that expected based on previous observations with Spitzer, possibly due to hazes absorbing in the NIR or non-solar compositions. The degeneracy of models with different compositions and temperature structures combined with the low amplitude ofmore » any features in the data preclude our ability to place unambiguous constraints on the atmospheric composition without additional observations with WFC3 to improve the signal-to-noise ratio and/or a comprehensive multi-wavelength analysis.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  2. Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)
  3. Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06511 (United States)
  4. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
  5. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
Publication Date:
OSTI Identifier:
22348405
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 779; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; AMPLITUDES; LIMITING VALUES; PHOTONS; PLANETS; SIGNAL-TO-NOISE RATIO; SPACE; SPECTRA; SPECTROSCOPY; TELESCOPES; VISIBLE RADIATION; WATER; WAVELENGTHS