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

Summary, in English

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 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.

• Author: S. Hoyer; D. Gandolfi; D. J. Armstrong; M. Deleuil; L. Acuña; J. R. De Medeiros; E. Goffo; J. Lillo-Box; E. Delgado Mena; T. A. Lopez; A. Santerne; S. Sousa; M. Fridlund; V. Adibekyan; K. A. Collins; L. M. Serrano; P. Cortés-Zuleta; S. B. Howell; H. Deeg; A. Aguichine; O. Barragán; E. M. Bryant; B. L. Canto Martins; K. I. Collins; B. F. Cooke; R. F. Díaz; M. Esposito; E. Furlan; S. Hojjatpanah; J. Jackman; J. M. Jenkins; E. L.N. Jensen; D. W. Latham; I. C. Leão; R. A. Matson; L. D. Nielsen; A. Osborn; J. F. Otegi; F. Rodler; S. Sabotta; N. J. Scott; S. Seager; C. Stockdale; P. A. Strøm; R. Vanderspek; V. Van Eylen; P. J. Wheatley; J. N. Winn; J. M. Almenara; D. Barrado; S. C.C. Barros; D. Bayliss; F. Bouchy; P. T. Boyd; J. Cabrera; W. D. Cochran; O. Demangeon; J. P. Doty; X. Dumusque; P. Figueira; W. Fong; S. Grziwa; A. P. Hatzes; P. Kabáth; E. Knudstrup; J. Korth; J. H. Livingston; R. Luque; O. Mousis; S. E. Mullally; H. P. Osborn; E. Pallé; C. M. Persson; S. Redfield; N. C. Santos; J. Smith; J. Šubjak; J. D. Twicken; S. Udry; D. A. Yahalomi
• Publishing year: 2021-08-01
• Language: English
• Pages: 3361-3379
• Publication/Series: Monthly Notices of the Royal Astronomical Society
• Volume: 505
• Issue: 3
• Links: http://dx.doi.org/10.1093/mnras/stab1427
• Document type: Journal article
• Publisher: Oxford University Press
• Keywords: planets and satellites: fundamental parameters; planets and satellites: individual: TYC 8897-01263-1; stars: fundamental parameters; techniques: photometric; techniques: radial velocities
• Status: Published
• ISBN/ISSN/Other: ISSN: 0035-8711