A transiting rocky super-Earth and a non-transiting sub-Neptune orbiting the M dwarf TOI-771
Year: 2025
Type: article
Abstract: 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 Rb = 1.36 ± 0.10 R⊕ and Mb = 2.47−0.31+0.32M⊕ 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 Teq =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 Mp sin i = 2.87−0.38+0.41M⊕. 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: G. Lacedelli, E. Pallé, Y. T. Davis, R. Luque, G. Morello, H. M. Tabernero, M. R. Zapatero Osorio, F. J. Pozuelos, D. Jankowski, G. Nowak, F. Murgas, J. Orell-Miquel, J. M. Akana Murphy, K. Barkaoui, D. Charbonneau, G. Dransfield, E. Ducrot, S. Geraldía-González, J. Irwin, E. Jehin, H. L. M. Osborne, P. P. Pedersen, B. V. Rackham, M. G. Scott, M. Timmermans, A. Triaud, V. Van Eylen
Institutions: Instituto de Astrofísica de Canarias, Universidad de La Laguna, University of Birmingham, Institute of Space Sciences, Institut d'Estudis Espacials de Catalunya, Centro de Astrobiología, ETH Zurich, Institute for Particle Physics and Astrophysics, University of Liège, University College London, University of Cambridge, Massachusetts Institute of Technology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
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, 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
Awards: G101150294, G1129048233, G1175115578, G121809054, G1380325028, G1381791653, G1401168639, G1430117670, G1622782223, G1706122712, G1814045685, G1853635042, G1855990336, G18599350, Red-enhanced cameras to seek rocky planets transiting Ultra-Cool Dwarfs, G2171960263, G2191281307, G2262748287, G2309174360, G2342240252, G24120701, The MEarth Project: An All Sky Survey of the Closest Low-mass Stars to Uncover the Very Best Terrestrial Exoplanets for Further Study, G252646220, G2579336268, G2601397997, G2660406951, G294895050, G2956311059, G300979063, G3106129878, G3207356259, G3452655474, G3480869486, G3518538256, The MEarth Project: A Transit Search for Rocky Planets in the Habitable Zones of Low-mass Stars, G3681454997, DISCOVERY AND ATMOSPHERIC RECONNAISSANCE OF THE MOST SPECTROSCOPICALLY ACCESSIBLE TEMPERATE TRANSITING TERRESTRIAL EXOPLANETS, G3817602061, G4002467474, G4042783231, G410571670, G4126913923, G4252671623, G425668148, Phasenübergänge und Instabilitäten, G430777504, G433322167, G4334099265, G4442677895, G451917667, G4526231891, G463062595, G496129201, G5080475149, Graduate Research Fellowship Program(GRFP), G5195188938, G523076202, G5421974903, G5539308778, G5580121929, G5811331711, G58316358, G5894067328, G5967599077, G5995483534, G6033112984, G6201089904, G6273510985, G6370911076, Temperate exoplanets from Chile & Antarctica, The MEarth Project: An All-sky Transit Search for Rocky Planets in the Habitable Zones of Low-mass Stars, 2009 Waterman Award, G6686480456, G7084143925, G7288031051, G7518687652, G7553243680, VLSI-Systeme mit optischen Verbindungen - Vorstudie der technologischen Machbarkeit -, G7719629023, G8211471405, Alexander von Humboldt and the Globalization of Science: Networks of Knowledge between Germany and the United States in the 19th Century, G8345352404, Characterization of the expression of Retinoic acid receptor during early chick development, Running costs of the Ganymede Telescope., G8575141037, G8597195001, G878044590, G8920660035, G896728979, G897484643, G99296377
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