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TOI-220 b: a warm sub-Neptune discovered by TESS

Hoyer, S; Gandolfi, D; Armstrong, DJ; Deleuil, M; Acuña, L; Medeiros, JRD; Goffo, E; ... Yahalomi, DA; + view all (2021) TOI-220 b: a warm sub-Neptune discovered by TESS. Monthly Notices of the Royal Astronomical Society , 505 (3) pp. 3361-3379. 10.1093/mnras/stab1427. Green open access

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Abstract

In this paper, we report the discovery of TOI-220 b, a new sub-Neptune detected by the Transiting Exoplanet Survey Satellite (TESS) and confirmed by radial velocity follow-up observations with the HARPS spectrograph. Based on the combined analysis of TESS transit photometry and high precision radial velocity measurements, we estimate a planetary mass of 13.8 ± 1.0 M⊕ and radius of 3.03 ± 0.15 R⊕, implying a bulk density of 2.73 ± 0.47 gcm−3⁠. TOI-220 b orbits a relative bright (V= 10.4) and old (10.1 ± 1.4 Gyr) K dwarf star with a period of ∼10.69 d. Thus, TOI-220 b is a new warm sub-Neptune with very precise mass and radius determinations. A Bayesian analysis of the TOI-220 b internal structure indicates that due to the strong irradiation it receives, the low density of this planet could be explained with a steam atmosphere in radiative–convective equilibrium and a supercritical water layer on top of a differentiated interior made of a silicate mantle and a small iron core.

Type: Article
Title: TOI-220 b: a warm sub-Neptune discovered by TESS
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/mnras/stab1427
Publisher version: https://doi.org/10.1093/mnras/stab1427
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: techniques: photometric, techniques: radial velocities, planets and satellites: fundamental parameters, planets and satellites: individual: TYC 8897-01263-1, stars: fundamental parameters
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 Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10129408
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