HST PanCET programme: a flat optical transmission spectrum for the Hot Jupiter WASP-101b. Issue 1 (6th April 2023)

• Record Type: Journal Article
• Authors: Rathcke, Alexander D; Buchhave, Lars A; Mendonça, João M; Sing, David K; López-Morales, Mercedes; Alam, Munazza K; Henry, Gregory W; Nikolov, Nikolay K; García Muñoz, A; Mikal-Evans, Thomas; Wakeford, Hannah R; Dos Santos, Leonardo A; Rajpaul, Vinesh Maguire
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 522:Issue 1(2023)
• Page Start: 582
• Page End: 594
• Publication Date: 2023-04-06
• Subjects: methods: data analysis -- methods: observational -- planets and satellites: atmospheres -- planets and satellites: gaseous planets; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stad1010
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present an optical transmission spectrum of the hot Jupiter WASP-101b. We observed three primary transits with Hubble Space Telescope ( HST )/Space Telescope Imaging Spectrograph, covering a wavelength range from 0.3 to 1 $\mu$ m. The observations suffer from significant systematics that we model using Gaussian Processes. Kernel selection for the Gaussian Processes is performed in a data-driven approach through Bayesian model comparison. We find a flat and featureless transmission spectrum, corroborating a previous measurement obtained with HST /Wide-Field Camera 3 in the 1–1.7 $\mu$ m range. The spectrum is consistent with high-altitude clouds located at less than 100 $\mu$ bar. This cloud layer completely blocks our view into deeper parts of the atmosphere and makes WASP-101b the cloudiest gas giant observed so far. We compute a series of temperature-pressure profiles for WASP-101b and compare these to condensation curves for cloud particles, which match clouds composed of silicates. We also include 13 transits observed with Transiting Exoplanet Survey Satellite and use these to refine system parameters.