HST PanCET program: A Cloudy Atmosphere for the promising JWST target WASP-101b

Abstract

We present results from the first observations of the Hubble Space Telescope (HST) Panchromatic Comparative Exoplanet Treasury (PanCET) 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 (WFC3) observation, we find that the near-infrared transmission spectrum of WASP-101b contains no significant H${}_2$O 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.

7 pages, 4 figures, 1 table, Accepted to ApJL

References in corpus (8)

• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• A Precise Water Abundance Measurement for the Hot Jupiter WASP-43b
• Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy
• HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering
• Transmission spectral properties of clouds for hot Jupiter exoplanets
• A consistent retrieval analysis of 10 Hot Jupiters observed in transmission
• High temperature condensate clouds in super-hot Jupiter atmospheres
• Near-infrared transmission spectrum of the warm-uranus GJ 3470b with the Wide Field Camera-3 on the Hubble Space Telescope

Cited by in corpus (11)

• An ultrahot gas-giant exoplanet with a stratosphere
• The Complete transmission spectrum of WASP-39b with a precise water constraint
• An inventory of atomic species in the atmosphere of WASP-121b using UVES high-resolution spectroscopy
• A Hubble PanCET Study of HAT-P-11b: A Cloudy Neptune with a Low Atmospheric Metallicity
• Hubble PanCET: An isothermal day-side atmosphere for the bloated gas-giant HAT-P-32Ab
• ACCESS: A Visual to Near-infrared Spectrum of the Hot Jupiter WASP-43b with Evidence of ${\mathrm{H}}_2\mathrm{O}$, but no evidence of Na or K
• A comparative study of WASP-67b and HAT-P-38b from WFC3 data
• The hot Neptune WASP-166 b with ESPRESSO III: A blue-shifted tentative water signal constrains the presence of clouds
• Transmission spectroscopy with VLT FORS2: a featureless spectrum for the low-density transiting exoplanet WASP-88b
• Tentative detection of titanium oxide in the atmosphere of WASP-69 b with a 4m ground-based telescope
• The Hubble PanCET Program: A Featureless Transmission Spectrum for WASP-29b and Evidence of Enhanced Atmospheric Metallicity on WASP-80b