Edwards, B;
Changeat, Q;
Baeyens, R;
Tsiaras, A;
Al-Refaie, A;
Taylor, J;
Yip, KH;
... Beaulieu, J-P; + view all
(2020)
ARES I: WASP-76 b, A Tale of Two HST Spectra.
The Astronomical Journal
, 160
(1)
, Article 8. 10.3847/1538-3881/ab9225.
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Abstract
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.
| Type: | Article |
|---|---|
| Title: | ARES I: WASP-76 b, A Tale of Two HST Spectra |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-3881/ab9225 |
| Publisher version: | https://doi.org/10.3847/1538-3881/ab9225 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Exoplanet atmospheres; Exoplanet atmospheric composition; Hubble Space Telescope |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10101299 |
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