A Population Study of Gaseous Exoplanets

By Angelos Tsiaras, Ingo P. Waldmann, T. Zingales, Marco Rocchetto, G. Morello, M. Damiano, K. Karpouzas, Giovanna Tinetti, Laura K. McKemmish, Jonathan Tennyson and 1 more. 2017

261 citations recorded by the source corpus.

We present here the analysis of 30 gaseous extrasolar planets, with temperatures between 600 and 2400 K and radii between 0.35 and 1.9 RJup. The quality of the HST/WFC3 spatially scanned data combined with our specialized analysis tools allow us to study the largest and most self-consistent sample of exoplanetary transmission spectra to date and examine the collective behavior of warm and hot gaseous planets rather than isolated case studies. We define a new metric, the Atmospheric Detectability Index (ADI) to evaluate the statistical significance of an atmospheric detection and find statistically significant atmospheres in around 16 planets out of the 30 analyzed. For most of the Jupiters in our sample, we find the detectability of their atmospheres to be dependent on the planetary radius but not on the planetary mass. This indicates that planetary gravity plays a secondary role in the state of gaseous planetary atmospheres. We detect the presence of water vapour in all of the statistically detectable atmospheres, and we cannot rule out its presence in the atmospheres of the others. In addition, TiO and/or VO signatures are detected with 4σ confidence in WASP-76 b, and they are most likely present in WASP-121 b. We find no correlation between expected signal-to-noise and atmospheric detectability for most targets. This has important implications for future large-scale surveys.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

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Citations in the corpus

The 2020 release of the ExoMol database: Molecular line lists for exoplanet and other hot atmospheres (2020, methodology): “H2O, Papers XIX and XXX Water is one of the most widely studied molecules and its spectrum has been detected in a variety of exoplanets, in many cases as the only clearly identifiable molecule [206, 215].”
The ExoMol database: Molecular line lists for exoplanet and other hot atmospheres (2016, methodology): “H2O, Papers XIX and XXX Water is one of the most widely studied molecules and its spectrum has been detected in a variety of exoplanets, in many cases as the only clearly identifiable molecule [206, 215].”
Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e (2020, background): “…parameterizations have been included in retrievals of transmission spectra of exoplanets (see MacDonald & Madhusudhan 2017; Fisher & Heng 2018; Tsiaras et al. 2018; Pinhas et al. 2019; Barstow 2020, for some recent examples), cloudy retrievals are still a comparatively novel approach for…”
Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects (2019, background): “VI. Detection of sodium in WASP-52b’s cloudy atmosphere.”
An Accurate, Extensive, and Practical Line List of Methane for the HITEMP Database (2020, background): “Studies of transiting exoplanets have been able to probe the atmospheres of a small number of these objects (Tsiaras et al. 2018), with observations of water vapor (Grillmair et al. 2008) and carbon monoxide absorption (Konopacky et al. 2013).”