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

August 2021 • 2021MNRAS.505.3361H

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.

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.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2021MNRAS.505.3361H
• PDF http://academic.oup.com/mnras/pdf-lookup/doi/10.1093/mnras/stab1427
• PDF https://academic.oup.com/mnras/pdf-lookup/doi/10.1093/mnras/stab1427
• PREPRINT http://arxiv.org/abs/2105.01944
• DATA http://archive.eso.org/bin/ads2eso?2021MNRAS.505.3361H
• DATA https://archive.gemini.edu/searchform/publication=2021MNRAS.505.3361H
• DATA https://irsa.ipac.caltech.edu/bibdata/2021/H/2021MNRAS.505.3361H.html
• ELECTR https://doi.org/10.1093%2Fmnras%2Fstab1427