Characterization of two new transiting sub-Neptunes and a terrestrial planet around M-dwarf hosts
Year: 2026
Type: article
Abstract: We report the confirmation of three transiting exoplanets orbiting TOI-1243 (LSPM J0902+7138), TOI-4529 (G 2-21), and TOI-5388 (Wolf 346) that were initially detected by TESS through ground-based photometry and radial velocity follow-up measurements with CARMENES. The planets present short orbital periods of 4.65, 5.88, and 2.59 days, and they orbit early-M dwarfs (M2.0 V, M1.5 V, and M3.0 V, respectively). We were able to precisely determine the radius of all three planets with a precision of <7%, the mass of TOI-1243 b with a precision of 19%, and upper mass limits for TOI-4529 b and TOI-5388 b. The radius of TOI-1243 b is 2.33 ± 0.12 R⊕, its mass is 7.7 ± 1.5 M⊕, and the mean density is 0.61 ± 0.15 ρ⊕. The radius of TOI-4529b is 1.77−0.08+0.09 R⊕, the 3σ upper mass limit is 4.9 M⊕, and the 3σ upper density limit is 0.88 ρ⊕. The third planet, TOI-5388 b, is Earth-sized with a radius of 0.99−0.06+0.07 R⊕, a 3σ upper mass limit of 2.2 M⊕, and a 3σ upper density limit of 2.2 ρ⊕. While TOI-5388 b is most probably rocky, given its Earth-like radius, TOI-1243 b and TOI-4529 b are located in a highly degenerate region in the mass-radius space. TOI-4529 b appears to lean toward a water-world composition. TOI-1243 b has enough mass to host a significant H-He envelope, although a water-world and pure rocky compositions are also consistent with the data. Our analysis indicates that future atmospheric observations using JWST can aid in determining their real composition. The sample of small planets around M dwarfs is widely used to understand planet formation and composition theories, and our study adds three planets to this sample.
Authors: E. Poultourtzidis, G. Lacedelli, E. Pallé, I. Carleo, C. Magliano, S. Geraldía-González, J. A. Caballero, G. Morello, J. Orell-Miquel, H. M. Tabernero, F. Murgas, G. Covone, F. J. Pozuelos, P. J. Amado, V. J. S. Béjar, S. Chairetas, C. Cifuentes, D. R. Ciardi, K. A. Collins, I. J. M. Crossfield, E. Esparza-Borges, G. Fernández-Rodríguez, A. Fukui, Y. Hayashi, A. P. Hatzes, Th. Henning, E. Herrero, K. Horne, S. B. Howell, K. Isogai, J. M. Jenkins, Y. Kawai, F. Libotte, E. Matthews, P. Meni-Gallardo, I. Mireles, J. C. Morales, N. Narita, B. B. Ogunwale, H. Parviainen, A. Quirrenbach, A. Reiners, I. Ribas, R. Sefako, A. Shporer, R. P. Schwarz, G. Srdoc, L. Tal-Or, S. Vanaverbeke, N. Watanabe, C. N. Watkins, F. Zong Lang
Institutions: Aristotle University of Thessaloniki, Instituto de Astrofísica de Canarias, Universidad de La Laguna, Osservatorio Astrofisico di Torino, European Space Astronomy Centre, Centro de Astrobiología, Osservatorio Astronomico di Palermo, Instituto de Astrofísica de Andalucía, National Institute for Astrophysics, The University of Texas at Austin, Institute of Space Sciences, Institut d'Estudis Espacials de Catalunya, California Institute of Technology, NASA Exoplanet Science Institute, Center for Astrophysics Harvard & Smithsonian, University of Kansas, The University of Tokyo, Thüringer Landessternwarte Tautenburg, University of St Andrews, Ames Research Center, Kyoto University, Max Planck Institute for Astronomy, University of New Mexico, 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, National Aeronautics and Space Administration, California Institute of Technology, Space Telescope Science Institute, Deutsche Forschungsgemeinschaft, Universidad Complutense de Madrid, Ministerio de Economía y Competitividad, Ministry of Science, ICT and Future Planning, Max-Planck-Gesellschaft, Ministerio de Ciencia e Innovación, Klaus Tschira Stiftung, Junta de Andalucía, Instituto de Astrofísica de Andalucía, Max-Planck-Institut für Astronomie, Instituto de Astrofísica de Canarias, Ames Research Center, Science Mission Directorate, Japan Society for the Promotion of Science, Consejo Superior de Investigaciones Científicas, European Regional Development Fund, Agencia Estatal de Investigación, Integrated Electronics Engineering Center, Binghamton University, Precursory Research for Embryonic Science and Technology
Awards: G1171257612, G1175115578, G1353885700, G1381791653, TTV法によるM型星まわりの小型惑星の組成分布とその起源の解明, G1839585985, G1855990336, G1877798660, G2030784793, G2262748287, G2309174360, G2499501003, G2627485041, G2633884080, G2660406951, G278595929, G300979063, G302750986, G3439265645, G3480869486, G3752857035, G3817602061, G410571670, G4190160184, G425668148, G430777504, G4502305455, G451917667, G463062595, G4796750904, 原子炉による悪性皮膚腫瘍の選択的治療, G5080475149, G5222444068, G5421974903, G5539308778, G5894067328, G5967599077, G617610489, G6180974586, G6326031618, G6379254292, G7053437819, G7084143925, G7130151326, G753082317, 古代説話における諸寺縁起の研究, G8028352098, G8308124115, G8347645112, A Study for Unveiling Planetary Evolution with Young Transiting Exoplanets, G8430294048, G8662767329, G8688487427, G869884560, G8739736297, G8920660035, G99296377
OpenAlex ID: W7124448374
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