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ARES I: WASP-76 b, A Tale of Two HST Spectra*


Edwards, B and Changeat, Q and Baeyens, R and Tsiaras, A and Al-Refaie, A and Taylor, J and Yip, KH and Bieger, MF and Blain, D and Gressier, A and Guilluy, G and Jaziri, AY and Kiefer, F and Modirrousta-Galian, D and Morvan, M and Mugnai, LV and Pluriel, W and Poveda, M and Skaf, N and Whiteford, N and Wright, S and Zingales, T and Charnay, B and Drossart, P and Leconte, J and Venot, O and Waldmann, I and Beaulieu, J, ARES I: WASP-76 b, A Tale of Two HST Spectra*, The Astronomical Journal, 160, (1) Article 8. ISSN 0004-6256 (2020) [Refereed Article]

Copyright Statement

2020. The American Astronomical Society. All rights reserved.

DOI: doi:10.3847/1538-3881/ab9225


We analyze the transmission and emission spectra of the ultra-hot Jupiter WASP-76 b, observed with the G141 grism of the Hubble Space Telescope's (HST) Wide Field Camera 3 (WFC3). We reduce and fit the raw data for each observation using the open-source software Iraclis before performing a fully Bayesian retrieval using the publicly available analysis suite TauREx 3. Previous studies of the WFC3 transmission spectra of WASP-76 b found hints of titanium oxide (TiO) and vanadium oxide (VO) or non-gray clouds. Accounting for a fainter stellar companion to WASP-76, we reanalyze this data and show that removing the effects of this background star changes the slope of the spectrum, resulting in these visible absorbers no longer being detected, eliminating the need for a non-gray cloud model to adequately fit the data but maintaining the strong water feature previously seen. However, our analysis of the emission spectrum suggests the presence of TiO and an atmospheric thermal inversion, along with a significant amount of water. Given the brightness of the host star and the size of the atmospheric features, WASP-76 b is an excellent target for further characterization with HST, or with future facilities, to better understand the nature of its atmosphere, to confirm the presence of TiO and to search for other optical absorbers.

Item Details

Item Type:Refereed Article
Keywords:Exoplanet atmospheres; Exoplanet atmospheric composition; Hubble Space Telescope
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Beaulieu, J (Dr Jean-Philippe Beaulieu)
ID Code:152248
Year Published:2020
Web of Science® Times Cited:43
Deposited By:Plant Science
Deposited On:2022-08-15
Last Modified:2022-11-24

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