A transiting rocky super-Earth and a non-transiting sub-Neptune orbiting the M dwarf TOI-771
Context. The origin and evolution of the sub-Neptune population is a highly debated topic in the exoplanet community. With the advent of JWST , atmospheric studies can now put unprecedented constraints on the internal composition of this population. In this context, the THIRSTEE project aims to investigate the population properties of sub-Neptunes with a comprehensive and demographic approach, providing a homogeneous sample of precisely characterised sub-Neptunes across stellar spectral types. Aims. We present here the precise characterisation of the planetary system orbiting one of the THIRSTEE M-dwarf targets, TOI-771 ( d = 25 pc, V = 14.9 mag), known to host one planet, TOI-771 b, which has been statistically validated using TESS observations. Methods. We use TESS , SPECULOOS, TRAPPIST, and M-Earth photometry together with 31 high-precision ESPRESSO radial velocities to derive the orbital parameters and investigate the internal composition of TOI-771 b, as well as exploring the presence of additional companions in the system. Results. We derived the precise mass and radius for TOI-771 b, a super-Earth with R b = 1.36 ± 0.10 R ⊕ and M b = 2.47 −0.31 +0.32 M ⊕ orbiting every 2.3 days around its host star. Its composition is consistent with an Earth-like planet, and it adds up to the rocky population of subNeptunes lying below the density gap identified around M dwarfs. With a ∼ 13% precision in mass, a∼ 7% radius precision, and a warm equilibrium temperature of T eq =543K, TOI-771 b is a particularly interesting target for atmospheric characterisation with JWST , and it is indeed one of the targets under consideration for the Rocky World DDT programme. Additionally, we discover the presence of a second, non-transiting planet in the system, TOI-771 c, with a period of 7.61 days and a minimum mass of M p sin i = 2.87 −0.38 +0.41 M ⊕ . Even though the inclination is not directly constrained, the planet likely belongs to the temperate sub-Neptune population, with an equilibrium temperature of ∼ 365K.
Authors
- B. V. Rackham
- R. Luque (ORCID: https://orcid.org/0000-0002-4671-2957)
- F. J. Pozuelos (ORCID: https://orcid.org/0000-0003-1572-7707)
- F. Murgas (ORCID: https://orcid.org/0000-0001-9087-1245)
- D. Charbonneau
- Ε. Πάλλη (ORCID: https://orcid.org/0000-0003-0987-1593)
- M. R. Zapatero Osorio (ORCID: https://orcid.org/0000-0001-5664-2852)
- Yasmin Davis (ORCID: https://orcid.org/0009-0000-6625-137X)
- A. H. M. J. Triaud (ORCID: https://orcid.org/0000-0002-5510-8751)
- H. L. M. Osborne (ORCID: https://orcid.org/0000-0002-4143-4767)
- G. Lacedelli (ORCID: https://orcid.org/0000-0002-4197-7374)
- Mathilde Timmermans (ORCID: https://orcid.org/0009-0008-2214-5039)
- Khalid Barkaoui (ORCID: https://orcid.org/0000-0003-1464-9276)
- J. Orell-Miquel (ORCID: https://orcid.org/0000-0003-2066-8959)
- V. Van Eylen
- Dawid Jankowski (ORCID: https://orcid.org/0000-0002-2013-0254)
- E. Jehin
- Pauli Pedersen (ORCID: https://orcid.org/0000-0001-8912-8147)
- G. Nowak
- Joseph M. Akana Murphy (ORCID: https://orcid.org/0000-0001-8898-8284)
- H. M. Tabernero (ORCID: https://orcid.org/0000-0002-8087-4298)
- Elsa Ducrot (ORCID: https://orcid.org/0000-0002-7008-6888)
- G. Dransfield
- S. Geraldía-González (ORCID: https://orcid.org/0009-0002-5545-3034)
- Jonathan Irwin
- Giuseppe Morello (ORCID: https://orcid.org/0000-0002-4262-5661)
- M. G. Scott (ORCID: https://orcid.org/0009-0006-3846-4558)
Publication Details
- Journal
- Astronomy and Astrophysics
- Published
- 2025-05-06
- DOI
- https://doi.org/10.1051/0004-6361/202554161
- Citations
- 1
- Primary Topic
- Astro and Planetary Science
- Type
- article
- Field-Weighted Citation Impact
- 1.15
Funders
- National Science Foundation
- Smithsonian Institution
- National Aeronautics and Space Administration
- John Templeton Foundation
- California Institute of Technology
- Harvard University
- Magdalen College, University of Oxford
- Space Telescope Science Institute
- European Space Agency
- European Commission
- Indian Council of Agricultural Research
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Fonds De La Recherche Scientifique - FNRS
- Fédération Wallonie-Bruxelles
- Ministry of Science, ICT and Future Planning
- Nuclear Safety and Security Commission
- Ministerio de Ciencia e Innovación
- Fondation Francqui - Stichting
- Ames Research Center
- Smithsonian Astrophysical Observatory
- Science Mission Directorate
- Science and Technology Facilities Council
- Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture
- European Regional Development Fund
- Agencia Estatal de Investigación