HST PanCET Program: a cloudy atmosphere for the promising JWST Target WASP-101b
García Muñoz, A
Lecavelier des Etangs, A
American Astronomical Society / IOP Publishing
© 2017. The American Astronomical Society. All rights reserved.
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.
This research has made use of NASA’s Astrophysics Data System and components of the IDL astronomy library. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-14767. H.R.W. acknowledges support by an appointment to the NASA Postdoctoral Program at Goddard Space Flight Center, administered by USRA through a contract with NASA. D.K.S., N.N., and T.E. acknowledge funding from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No. 336792. J.K.B. is supported by a Royal Astronomical Society Research Fellowship. D.E. acknowledges the financial support of the National Centre for Competence in Research “PlanetS” supported by the Swiss National Science Foundation (SNSF). L.B.-J., P.L., and A.L. acknowledge support from CNES (France) under project PACES. The authors would like to thank the referee for their careful examination of this Letter. Facility: HST (WFC3).
This is the final version of the article. Available from the publisher via the DOI in this record.
Vol. 835, L12