Planet(esimal)s around stars with TESS (PAST) III

Autor(en): Eric Gaidos, Teruyuki Hirano, Rena A. Lee, Hiroki Harakawa, Klaus Hodapp, Shane Jacobson, Takayuki Kotani, Tomoyuki Kudo, Takashi Kurokawa, Masayuki Kuzuhara, Jun Nishikawa, Masashi Omiya, Takuma Serizawa, Motohide Tamura, Akitoshi Ueda, Sebastien Vievard
Abstrakt: We report a search for excess absorption in the 1083.2 nm line of ortho (triplet) helium during transits of TOI-1807b and TOI-2076b, 1.25 and 2.5-R_⊕ planets on 0.55- and 10.4-d orbits around nearby ∼200 Myr-old K dwarf stars. We limit the equivalent width of any transit-associated absorption to <4 and <8 mÅ, respectively. We limit the escape of solar-composition atmospheres from TOI-1807b and TOI-2076b to ≾1 and ≾0.1M_⊕Gyr⁻¹, respectively, depending on wind temperature. The absence of a H/He signature for TOI-1807b is consistent with a measurement of mass indicating a rocky body and the prediction by a hydrodynamic model that any H-dominated atmosphere would be unstable and already have been lost. Differential spectra obtained during the transit of TOI-2076b contain a He I-like feature, but this closely resembles the stellar line and extends beyond the transit interval. Until additional transits are observed, we suspect this to be the result of variation in the stellar He I line produced by rotation of active regions and/or flaring on the young, active host star. Non-detection of escape could mean that TOI-2076b is more massive than expected, the star is less EUV luminous, the models overestimate escape, or the planet has a H/He-poor atmosphere that is primarily molecules such as H₂O. Photochemical models of planetary winds predict a semimajor axis at which triplet He I observations are most sensitive to mass-loss: TOI-2076b orbits near this optimum. Future surveys could use a distance criterion to increase the yield of detections.
Organisation(en): Institut für Astrophysik
Externe Organisation(en): University of Hawaii at Manoa, Eidgenössische Technische Hochschule Zürich, National Astronomical Observatory of Japan, Graduate University for Advanced Studies , University of Hawaii, Tokyo University of Agriculture and Technology, University of Tokyo
Journal: Monthly Notices of the Royal Astronomical Society
Band: 518
Seiten: 3777-3783
Anzahl der Seiten: 7
ISSN: 0035-8711
DOI: https://doi.org/10.1093/mnras/stac3301
Publikationsdatum: 01-2023
Peer-reviewed: Ja
ÖFOS 2012: 103003 Astronomie, 103004 Astrophysik
Schlagwörter
ASJC Scopus Sachgebiete: Astronomy and Astrophysics, Space and Planetary Science
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/2a27c538-972f-4e88-b3e7-c2ad90ba1c25

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