Three super-Earths and a possible water world from TESS and ESPRESSO^★

¹ Observatoire de Genève, Département d’Astronomie, Université de Genève, Chemin Pegasi 51b, 1290 Versoix, Switzerland
e-mail: melissa.hobson@unige.ch
² Instituto de Astrofísica e Ciências do Espaço, CAUP, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
³ Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
⁴ Instituto de Astrofísica de Canarias, c/ Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
⁵ Physics Institute, University of Bern, Gesellsschaftstrasse 6, 3012 Bern, Switzerland
⁶ Center for Space and Habitability, University of Bern, Gesellss-chaftstrasse 6, 3012 Bern, Switzerland
⁷ Centro de Astrobiología (CAB), CSIC-INTA, Camino Bajo del Castillo s/n, 28692, Villanueva de la Cañada (Madrid), Spain
⁸ INAF – Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34143, Trieste, Italy
⁹ INAF – Osservatorio Astrofisico di Torino, Strada Osservatorio 20, 10025, Pino Torinese (TO), Italy
¹⁰ European Southern Observatory, Av. Alonso de Cordova, 3107, Vitacura, Santiago de Chile, Chile
¹¹ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
¹² Universidad de La Laguna, Dept. Astrofísica, E-38206 La Laguna, Tenerife, Spain
¹³ Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
¹⁴ INAF – Osservatorio Astronomico di Palermo, Piazza del Parla-mento 1, 90134 Palermo, Italy
¹⁵ Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal
¹⁶ Observatoire François-Xavier Bagnoud – OFXB, 3961 Saint-Luc, Switzerland
¹⁷ Departamento de Física de la Tierra y Astrofísica & IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos de la UCM), Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
¹⁸ Centre for Exoplanets and Habitability, University of Warwick, Coventry, CV4 7AL, UK
¹⁹ Department of Physics, University of Warwick, Coventry CV4 7AL, UK
²⁰ Caltech/IPAC-NASA Exoplanet Science Institute, 770 S. Wilson Avenue, Pasadena, CA 91106, USA
²¹ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
²² George Mason University, 4400 University Drive, Fairfax, VA 22030, USA
²³ NSF’s National Optical-Infrared Astronomy Research Laboratory, 950 N. Cherry Avenue, Tucson, AZ 85719, USA
²⁴ Dipartimento di Fisica, Università degli Studi di Torino, Via Pietro Giuria, 1, 10125, Torino, Italy
²⁵ NASA Ames Research Center, Moffett Field, CA 94035, USA
²⁶ Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292, USA
²⁷ Astrobiology Center, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
²⁸ National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
²⁹ Department of Physics and Astronomy, University of New Mexico, 210 Yale Blvd NE, Albuquerque, NM 87106, USA
³⁰ Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
³¹ Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
³² Department of Aeronautics and Astronautics, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
³³ Perth Exoplanet Survey Telescope, Perth, Western Australia, Australia
³⁴ Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA

Received: 25 April 2024
Accepted: 10 June 2024

Abstract

Context. Since 2018, the ESPRESSO spectrograph at the VLT has been hunting for planets in the southern skies via the radial velocity (RV) method. One of its goals is to follow up on candidate planets from transit surveys such as the TESS mission, with a particular focus on small planets for which ESPRESSO’s RV precision is vital.

Aims. We aim to confirm and characterise, in detail, three super-Earth candidate transiting planets from TESS using precise RVs from ESPRESSO.

Methods. We analysed photometry from TESS and ground-based facilities, high-resolution imaging, and RVs from ESPRESSO, HARPS, and HIRES, to confirm and characterise three new planets: TOI-260 b, transiting a late K dwarf, and TOI-286 b and c, orbiting an early K dwarf. We also updated the parameters for the known super-Earth TOI-134 b (L 168-9 b), which is hosted by an M dwarf.

Results. TOI-260 b has a 13.475853_−0.000011^+0.000013 d period, 4.23 ± 1.60 M_⊕ mass, and 1.71 ± 0.08 R_⊕ radius. For TOI-286 b we find a 4.5117244_−0.0000027^+0.0000031 d period, 4.53 ± 0.78 M_⊕ mass, and 1.42 ± 0.10 R_⊕ radius; for TOI-286 c, we find a 39.361826_−0.000081^+0.000070 d period, 3.72 ± 2.22 M_⊕ mass, and 1.88 ± 0.12 R_⊕ radius. For TOI-134 b we obtain a 1.40152604_{−0.00000082}^+0.00000074 d period, 4.07 ± 0.45 M_⊕ mass, and 1.63 ± 0.14 R_⊕ radius. Circular models are preferred for all the planets, although for TOI-260 b the eccentricity is not well constrained. We computed bulk densities and placed the planets in the context of composition models.

Conclusions. TOI-260 b lies within the radius valley, and is most likely a rocky planet. However, the uncertainty on the eccentricity and thus on the mass renders its composition hard to determine. TOI-286 b and c span the radius valley, with TOI-286 b lying below it and having a likely rocky composition, while TOI-286 c is within the valley, close to the upper border, and probably has a significant water fraction. With our updated parameters for TOI-134 b, we obtain a lower density than previous findings, giving a rocky or Earth-like composition.