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Hot exoplanet atmospheres resolved with transit spectroscopy (HEARTS)VII. Detection of sodium on the long-transiting inflated sub-Saturn KELT-11 b★
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(2022) Hot exoplanet atmospheres resolved with transit spectroscopy (HEARTS)VII. Detection of sodium on the long-transiting inflated sub-Saturn KELT-11 b★. Astronomy & Astrophysics, 668 . A1. doi:10.1051/0004-6361/202243998 ISSN 0004-6361.
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Official URL: http://doi.org/10.1051/0004-6361/202243998
Abstract
Context. WASP-121 b is a hot Jupiter that was recently found to possess rich emission (day side) and transmission (limb) spectra, suggestive of the presence of a multitude of chemical species in the atmosphere.
Aims. We survey the transmission spectrum of WASP-121 b for line-absorption by metals and molecules at high spectral resolution and elaborate on existing interpretations of the optical transmission spectrum observed with the Hubble Space Telescope (HST).
Methods. We applied the cross-correlation technique and direct differential spectroscopy to search for sodium and other neutral and ionised atoms, TiO, VO, and SH in high-resolution transit spectra obtained with the HARPS spectrograph. We injected models assuming chemical and hydrostatic equilibrium with a varying temperature and composition to enable model comparison, and employed two bootstrap methods to test the robustness of our detections.
Results. We detect neutral Mg, Na, Ca, Cr, Fe, Ni, and V, which we predict exists in equilibrium with a significant quantity of VO, supporting earlier observations by HST/WFC3. Non-detections of Ti and TiO support the hypothesis that Ti is depleted via a cold-trap mechanism, as has been proposed in the literature. Atomic line depths are under-predicted by hydrostatic models by a factor of 1.5 to 8, confirming recent findings that the atmosphere is extended. We predict the existence of significant concentrations of gas-phase TiO2, VO2, and TiS, which could be important absorbers at optical and near-IR wavelengths in hot Jupiter atmospheres. However, accurate line-list data are not currently available for them. We find no evidence for absorption by SH and find that inflated atomic lines can plausibly explain the slope of the transmission spectrum observed in the near-ultraviolet with HST. The Na I D lines are significantly broadened (FWHM ~50 to 70 km s−1) and show a difference in their respective depths of ~15 scale heights, which is not expected from isothermal hydrostatic theory. If this asymmetry is of astrophysical origin, it may indicate that Na I forms an optically thin envelope, reminiscent of the Na I cloud surrounding Jupiter, or that it is hydrodynamically outflowing.
Item Type: | Journal Article | ||||||||||||||||||||||||
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Subjects: | Q Science > QB Astronomy | ||||||||||||||||||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||||||||||||||||||||
Library of Congress Subject Headings (LCSH): | Extrasolar planets, Extrasolar planets -- Atmopsheres, Astronomical spectroscopy, Extrasolar planets -- Detection, Astronomical photography | ||||||||||||||||||||||||
Journal or Publication Title: | Astronomy & Astrophysics | ||||||||||||||||||||||||
Publisher: | EDP Sciences | ||||||||||||||||||||||||
ISSN: | 0004-6361 | ||||||||||||||||||||||||
Official Date: | December 2022 | ||||||||||||||||||||||||
Dates: |
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Volume: | 668 | ||||||||||||||||||||||||
Article Number: | A1 | ||||||||||||||||||||||||
DOI: | 10.1051/0004-6361/202243998 | ||||||||||||||||||||||||
Status: | Peer Reviewed | ||||||||||||||||||||||||
Publication Status: | Published | ||||||||||||||||||||||||
Access rights to Published version: | Open Access (Creative Commons) | ||||||||||||||||||||||||
Copyright Holders: | © ESO 2020 | ||||||||||||||||||||||||
Date of first compliant deposit: | 9 February 2023 | ||||||||||||||||||||||||
Date of first compliant Open Access: | 9 February 2023 | ||||||||||||||||||||||||
RIOXX Funder/Project Grant: |
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