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 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.
Original language | English |
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Pages (from-to) | 3361-3379 |
Number of pages | 19 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 505 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2021 Aug 1 |
Externally published | Yes |
Bibliographical note
Funding Information:SH acknowledges the Centre National d'Etudes Spatiales (CNES) funding through the grant 837319. MD acknowledges the CNES support. VA, EDM, SGS, NCS, SCCB, and SHoj acknowledge support by FCT - Fundaç ão para a Ciência e a Tecnologia (Portugal) through national funds and by FEDER through COMPETE2020 - Programa Operacional Competitividade e Internacionalizaç ão by these grants: UID/FIS/04434/2019; UIDB/04434/2020; UIDP/04434/2020; PTDC/FIS-AST/32113/2017 & POCI- 01-0145-FEDER-032113; PTDC/FIS-AST/28953/2017 & POCI-01-0145-FEDER-028953. VA, EDM, SCCB, SGS, and ODSD further acknowledge the support from FCT through Investigador FCT contracts IF/00650/2015/CP1273/CT0001, IF/00849/2015/CP1273/CT0003, IF/01312/2014/CP1215/CT0004, CEECIND/00826/2018-POPH/FSE(EC), and DL57/2016/CP1364/ CT0004, respectively. SHoj further acknowledges the support by FCT through the fellowship PD/BD/128119/2016. DJA acknowledges support from the STFC via an Ernest Rutherford Fellowship (ST/R00384X/1). LMS and DG gratefully acknowledge financial support from the CRT foundation under Grant No. 2018.2323 'Gaseous or rocky? Unveiling the nature of small worlds'. JRM, BLCM, and ICL acknowledge continuous grants from the brazilian funding agencies CNPq, CAPES, and FAPERN. This study was financed in part by the Coordenaç ão de Aperfeiçoamento de Pessoal de Nível Superior-Brasil (CAPES)-Finance Code 001. PK and JS acknowledge the MSMT INTER-TRANSFER grant LTT20015. This paper includes data collected with the TESS mission, which are publicly available from the Mikulski Archive for Space Telescopes (MAST). Funding for the TESS mission is provided by NASA's Science Mission directorate. We acknowledge the use of public TESS Alert data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. This research has made use of the Exoplanet Follow-up Observation Program website, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. This research has made use of computing facilities operated by CeSAM data center at LAM, Marseille, France; and the Data & Analysis Center for Exoplanets (DACE), which is a facility based at the University of Geneva (CH) dedicated to extrasolar planets data visualization, exchange, and analysis. DACE is a platform of the Swiss National Centre of Competence in Research (NCCR) PlanetS, federating the Swiss expertise in Exoplanet research. This research has made use of data obtained from the portal exoplanet.eu of The Extrasolar Planets Encyclopaedia. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This work makes use of observations from the LCOGT network. DG warmly thanks Alessia Barbiero and Pietro Giordano for the inspiring conversations at the time the HARPS follow-up of TOI-220 was started in 2018 November.
Publisher Copyright:
© 2021 The Author(s).
Free keywords
- planets and satellites: fundamental parameters
- planets and satellites: individual: TYC 8897-01263-1
- stars: fundamental parameters
- techniques: photometric
- techniques: radial velocities