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The young mini-Neptune HD 207496b that is either a naked core or on the verge of becoming one
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(2023) The young mini-Neptune HD 207496b that is either a naked core or on the verge of becoming one. Astronomy & Astrophysics, 673 . A4. doi:10.1051/0004-6361/202245741 ISSN 0004-6361.
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Official URL: https://doi.org/10.1051/0004-6361/202245741
Abstract
Aims. We report the discovery and characterisation of the transiting mini-Neptune HD 207496 b (TOI-1099) as part of a large programme that aims to characterise naked core planets.
Methods. We obtained HARPS spectroscopic observations, one ground-based transit, and high-resolution imaging which we combined with the TESS photometry to confirm and characterise the TESS candidate and its host star.
Results. The host star is an active early K dwarf with a mass of 0.80 ± 0.04 M⊙, a radius of 0.769 ± 0.026 R⊙, and a G magnitude of 8. We found that the host star is young, ~0.52 Gyr, allowing us to gain insight into planetary evolution. We derived a planetary mass of 6.1 ± 1.6 M⊕, a planetary radius of 2.25 ± 0.12 R⊕, and a planetary density of ρp = 3.27−0.91+0.97 g cm−3.
Conclusions. From internal structure modelling of the planet, we conclude that the planet has either a water-rich envelope, a gas-rich envelope, or a mixture of both. We have performed evaporation modelling of the planet. If we assume the planet has a gas-rich envelope, we find that the planet has lost a significant fraction of its envelope and its radius has shrunk. Furthermore, we estimate it will lose all its remaining gaseous envelope in ~0.52 Gyr. Otherwise, the planet could have already lost all its primordial gas and is now a bare ocean planet. Further observations of its possible atmosphere and/or mass-loss rate would allow us to distinguish between these two hypotheses. Such observations would determine if the planet remains above the radius gap or if it will shrink and be below the gap.
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 -- Detection, Extrasolar planets -- Internal structure, Astronomical photometry, Astrophysics | |||||||||||||||||||||||||||||||||||||||||||||||||||
Journal or Publication Title: | Astronomy & Astrophysics | |||||||||||||||||||||||||||||||||||||||||||||||||||
Publisher: | EDP Sciences | |||||||||||||||||||||||||||||||||||||||||||||||||||
ISSN: | 0004-6361 | |||||||||||||||||||||||||||||||||||||||||||||||||||
Official Date: | May 2023 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Volume: | 673 | |||||||||||||||||||||||||||||||||||||||||||||||||||
Number of Pages: | 18 | |||||||||||||||||||||||||||||||||||||||||||||||||||
Article Number: | A4 | |||||||||||||||||||||||||||||||||||||||||||||||||||
DOI: | 10.1051/0004-6361/202245741 | |||||||||||||||||||||||||||||||||||||||||||||||||||
Status: | Peer Reviewed | |||||||||||||||||||||||||||||||||||||||||||||||||||
Publication Status: | Published | |||||||||||||||||||||||||||||||||||||||||||||||||||
Access rights to Published version: | Open Access (Creative Commons) | |||||||||||||||||||||||||||||||||||||||||||||||||||
Date of first compliant deposit: | 17 May 2023 | |||||||||||||||||||||||||||||||||||||||||||||||||||
Date of first compliant Open Access: | 19 May 2023 | |||||||||||||||||||||||||||||||||||||||||||||||||||
RIOXX Funder/Project Grant: |
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