HST PanCET Program: A Cloudy Atmosphere for the Promising JWST Target WASP-101b

H. R. Wakeford, K. B. Stevenson, N. K. Lewis, D. K. Sing, M. López-Morales, M. Marley, T. Kataria, A. Mandell, G. E. Ballester, J. Barstow, L. Ben-Jaffel, V. Bourrier, L. A. Buchhave, D. Ehrenreich, T. Evans, A. García Muñoz, G. Henry, H. Knutson, P. Lavvas, A. Lecavelier Des EtangsN. Nikolov, J. Sanz-Forcada

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

We present results from the first observations of the Hubble Space Telescope (HST) Panchromatic Comparative Exoplanet Treasury program for WASP-101b, a highly inflated hot Jupiter and one of the community targets proposed for the James Webb Space Telescope (JWST) Early Release Science (ERS) program. From a single HST Wide Field Camera 3 observation, we find that the near-infrared transmission spectrum of WASP-101b contains no significant H2O absorption features and we rule out a clear atmosphere at 13σ. Therefore, WASP-101b is not an optimum target for a JWST ERS program aimed at observing strong molecular transmission features. We compare WASP-101b to the well-studied and nearly identical hot Jupiter WASP-31b. These twin planets show similar temperature-pressure profiles and atmospheric features in the near-infrared. We suggest exoplanets in the same parameter space as WASP-101b and WASP-31b will also exhibit cloudy transmission spectral features. For future HST exoplanet studies, our analysis also suggests that a lower count limit needs to be exceeded per pixel on the detector in order to avoid unwanted instrumental systematics.

Original languageEnglish (US)
Article numberL12
JournalAstrophysical Journal Letters
Volume835
Issue number1
DOIs
StatePublished - Jan 20 2017

Keywords

  • planets and satellites: atmospheres
  • planets and satellites: individual (WASP-101b)
  • techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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