TOI-512: Super-Earth transiting a K-type star discovered by TESS and ESPRESSO^★

¹ Instituto de Astrofísica e Ciencias do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
² Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua Campo Alegre, 4169-007 Porto, Portugal
³ Observatoire François-Xavier Bagnoud – OFXB, 3961 Saint-Luc, Switzerland
⁴ Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland
⁵ Physics Institute of University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland
⁶ Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51b, 1290 Versoix, Switzerland
⁷ INAF – Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese, Italy
⁸ INAF – Osservatorio Astrofisico di Trieste, via G. B. Tiepolo 11, 34143, Trieste, Italy
⁹ IFPU–Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy
¹⁰ Department of Physics, Engineering and Astronomy, Stephen F. Austin State University, 1936 North St, Nacogdoches, TX 75962, USA
¹¹ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
¹² Universidad de La Laguna, Dept. Astrofísica, 38206 La Laguna, Tenerife, Spain
¹³ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748, Garching b. Munchen, Germany
¹⁴ European Southern Observatory, Alonso de Cordova 3107, Vitacura, Region Metropolitana, Chile
¹⁵ Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
¹⁶ Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA
¹⁷ INAF – Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
¹⁸ Fundación Galileo Galilei-INAF, Rambla José Ana Fernandez Pérez 7, 38712 Breña Baja, TF, Spain
¹⁹ Instituto de Astrofísica e Ciencias do Espaco, Faculdade de Ciencias da Universidade de Lisboa, Edifício C8, Campo Grande, 1749-016 Lisbon, Portugal
²⁰ Centro de Astrobiología, CSIC-INTA, Camino Bajo del Castillo s/n, 28602 Villanueva de la Cañada, Madrid, Spain

^★★ Corresponding author; jose.rodrigues@astro.up.pt

Received: 5 November 2024
Accepted: 10 February 2025

Abstract

Context. One of the goals of the ESPRESSO guaranteed time observations (GTOs) at the ESO 8.2 m telescope is to follow up on candidate planets from transit surveys such as the TESS mission. High-precision radial velocities are required to characterize small exoplanets.

Aims. We intend to confirm the existence of a transiting super-Earth around the bright (V=9.74) K0-type star TOI-512 (TIC 119292328) and provide a characterization.

Methods. Combining photometric data from TESS and 37 high-resolution spectroscopic observations from ESPRESSO in a joint Markov chain Monte Carlo analysis, we determined the planetary parameters of TOI-512b and characterized its internal structure.

Results. We find that TOI-512b is a super-Earth, with a radius of 1.54 ± 0.10 R⊕ and mass of 3.57−0.55+0.53 M⊕, on a 7.19−6.1·10−5+7.10−5 day orbit. This corresponds to a bulk density of 5.62−1.28+1.59 g cm−3. Our interior structure analysis presents a small inner core representing 0.13−0.11+0.13 of the solid mass fraction for the planet, surrounded by a mantle with a mass fraction of 0.69−0.22+0.20, and an upper limit of the water layer of 0.16. The gas mass below 10−8.93 indicates a very small amount of gas on the planet. We find no evidence of the second candidate found by the TESS pipeline, TOI-512.02, neither in TESS photometry, nor in the ESPRESSO radial velocities. The low stellar activity makes it an interesting transmission spectroscopy candidate for future-generation instruments.