TOI-220 b: a warm sub-Neptune discovered by TESS. Issue 3 (22nd May 2021)

• Record Type: Journal Article
• Authors: Hoyer, S; Gandolfi, D; Armstrong, D J; Deleuil, M; Acuña, L; de Medeiros, J R; Goffo, E; Lillo-Box, J; Delgado Mena, E; Lopez, T A; Santerne, A; Sousa, S; Fridlund, M; Adibekyan, V; Collins, K A; Serrano, L M; Cortés-Zuleta, P; Howell, S B; Deeg, H; Aguichine, A; Barragán, O; Bryant, E M; Canto Martins, B L; Collins, K I; Cooke, B F; Díaz, R F; Esposito, M; Furlan, E; Hojjatpanah, S; Jackman, J; Jenkins, J M; Jensen, E L N; Latham, D W; Leão, I C; Matson, R A; Nielsen, L D; Osborn, A; Otegi, J F; Rodler, F; Sabotta, S; Scott, N J; Seager, S; Stockdale, C; Strøm, P A; Vanderspek, R; Van Eylen, V; Wheatley, P J; Winn, J N; Almenara, J M; Barrado, D; Barros, S C C; Bayliss, D; Bouchy, F; Boyd, P T; Cabrera, J; Cochran, W D; Demangeon, O; Doty, J P; Dumusque, X; Figueira, P; Fong, W; Grziwa, S; Hatzes, A P; Kabáth, P; Knudstrup, E; Korth, J; Livingston, J H; Luque, R; Mousis, O; Mullally, S E; Osborn, H P; Pallé, E; Persson, C M; Redfield, S; Santos, N C; Smith, J; Šubjak, J; Twicken, J D; Udry, S; Yahalomi, D A;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 505:Issue 3(2021)
• Page Start: 3361
• Page End: 3379
• Publication Date: 2021-05-22
• Subjects: techniques: photometric -- techniques: radial velocities -- planets and satellites: fundamental parameters -- planets and satellites: individual: TYC 8897-01263-1 -- stars: fundamental parameters; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab1427
• Languages: English
• ISSNs: 0035-8711

Abstract

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 $\rm {g\, cm}^{-3}$ . 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.