ARES. II. Characterizing the Hot Jupiters WASP-127 b, WASP-79 b, and WASP-62b with the Hubble Space Telescope

The Hubble Space Telescope&#8217;s Wide Field Camera 3 (WFC3) has been widely used for transmission and emission spectroscopy of exoplanet atmospheres, identifying the main molecular constituents, detecting the presence of clouds and probing their thermal structure. Hubble observations of the emission spectra of a number of ultra-hot Jupiters have led to somewhat surprising results. Initially, these very hot planets were predicted to have inverted temperature pressure profiles due to strong optical absorption by TiO/VO in the upper atmospheres. However, observations of their emission spectra have been inconclusive on their thermal structure and composition. While some datasets show rich spectral features, others can be fit with simple blackbody models. We will present the analysis of Hubble WFC3 transmission and emission spectra for two ultra-hot Jupiters: WASP-76 b and KELT-7 b. In each case, the data was reduced and fitted using the open-source codes Iraclis and Taurex3. Previous studies of the WFC3 transmission spectra of WASP-76 b found hints of TiO and VO or non-grey clouds. Accounting for a fainter stellar companion to WASP-76, we reanalyse 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, removing the need for a non-grey 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 titanium oxide (TiO) and an atmospheric thermal inversion.&#160;Meanwhile, our study of KELT-7 b uncovers a rich transmission spectrum which suggests the presence of water and H-. In contrast, the extracted emission spectrum does not contain strong absorption features and, although it is not consistent with a simple blackbody, it can be explained by a varying temperature-pressure profile, collision induced absorption (CIA) and H-.&#160; These finding bring new insights into the nature of this intriguing class of planets but more data is required to fully understand them and thus we will also present the anticipated results of further characterisation.

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Cloud Atlas: Hubble Space Telescope Near-infrared Spectral Library of Brown Dwarfs, Planetary-mass Companions, and Hot Jupiters

The Astronomical Journal ◽

10.3847/1538-3881/aaf88f ◽

2019 ◽

Vol 157 (3) ◽

pp. 101 ◽

Cited By ~ 10

Author(s):

Elena Manjavacas ◽

Dániel Apai ◽

Yifan Zhou ◽

Ben W. P. Lew ◽

Glenn Schneider ◽

...

Keyword(s):

Near Infrared ◽

Hubble Space Telescope ◽

Brown Dwarfs ◽

Spectral Library ◽

Space Telescope ◽

Hot Jupiters ◽

Planetary Mass ◽

Infrared Spectral ◽

Cloud Atlas

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Characterising the Hot Jupiters WASP-127\,b, WASP-79\,b and WASP-62\,b with HST

10.5194/epsc2020-834 ◽

2020 ◽

Author(s):

Nour Skaf

Keyword(s):

Hubble Space Telescope ◽

Wide Field ◽

Space Telescope ◽

Hot Jupiters ◽

James Webb Space Telescope ◽

Cloudy Atmosphere ◽

Iron Hydride ◽

Short Period ◽

And Migration ◽

Best Fit

We would like to present the atmospheric characterisation of three large, gaseous planets: WASP-127b, WASP-79b and WASP-62b. We analysed spectroscopic data obtained with the G141 grism (1.088 - 1.68 um) of the Wide Field Camera 3 (WFC3) onboard the Hubble Space Telescope (HST) using the Iraclis pipeline and the TauREx3 retrieval code, both of which are publicly available. For WASP-127b, which is the least dense planet discovered so far and is located in the short-period Neptune desert, our retrieval results found strong water absorption corresponding to an abundance of log(H$_2$O) = -2.71$^{+0.78}_{-1.05}$, and absorption compatible with an iron hydride abundance of log(FeH)=$-5.25^{+0.88}_{-1.10}$, with an extended cloudy atmosphere. We also detected water vapour in the atmospheres of WASP-79b and WASP-62b, with best-fit models indicating the presence of iron hydride, too. We used the Atmospheric Detectability Index (ADI) as well as Bayesian log evidence to quantify the strength of the detection and compared our results to the hot Jupiter population study by Tsiaras et al 2018. While all the planets studied here are suitable targets for characterisation with upcoming facilities such as the James Webb Space Telescope (JWST) and Ariel, WASP-127b is of particular interest due to its low density, and a thorough atmospheric study would develop our understanding of planet formation and migration.&#160;

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