NIRPS and TESS reveal a peculiar system around the M dwarf TOI-756: A transiting sub-Neptune and a cold eccentric giant

作者：Léna Parc, F. Bouchy, Neil J. Cook, Nolan Grieves, Étienne Artigau, Alexandrine L’Heureux, René Doyon, Yuri S. Messias, Frédérique Baron, S. C. C. Barros, Björn Benneke, X. Bonfıls, Marta L. Bryan, B. L. Canto Martins, Ryan Cloutier, Nicolas B. Cowan, D. B. de Freitas, J. R. De Medeiros, X. Delfosse, E. Delgado Mena, X. Dumusque, D. Ehrenreich, P. Figueira, J. I. Gónzalez Hernández, David Lafreniére, I. C. Leão, C. Lovis, Lison Malo, C. Melo, L. Mignon, C. Mordasini, F. Pepe, R. Rébolo, Jason F. Rowe, N. C. Santos, D. Ségransan, A. Suárez Mascareño, S. Udry, Diana Valencia, G. A. Wade, Manuel Abreu, J. G. De S. Aguiar, Khaled Al Moulla, Guillaume Allain, Romain Allart, Jose Manuel Almenara, Tomy Arial, Hugues Auger, Luc Bazinet, Nicolas Blind, D. Bohlender, Isabelle Boisse, Anne Boucher, V. Bourrier, Sébastien Bovay, Pedro Soares Branco, C. Broeg, Denis Brousseau, Alexandre Cabral, Charles Cadieux, A. Carmona, Yann Carteret, Zalpha Challita, David Charbonneau, Bruno Chazelas, Catherine A. Clark, João M. P. Coelho, Marion Cointepas, Karen A. Collins, Kevin I. Collins, Uriel Conod, E. Cristo, Ana Rita Costa Silva, Antoine Darveau-Bernier, Laurie Dauplaise, J.-B. Delisle, R. L. Gomes, J. P. Faria, Dasaev O. Fontinele, T. Forveille, Yolanda G. C. Frensch, Jonathan Gagné, Frédéric Genest, Ludovic Genolet, J. Gomes da Silva, Félix Gracia Témich, Nicole Gromek, Olivier Hernandez, Mélissa J. Hobson, H. J. Hoeijmakers, Norbert Hubin, Marziye Jafariyazani, Farbod Jahandar, Ray Jayawardhana, Hans-Ulrich Käufl, Dan Kerley, J. Kolb, Vigneshwaran Krishnamurthy, Benjamin Küng, Pierrot Lamontagne, P. Larue, Henry Leath, Olivia Lim, G. Lo Curto, Allan Martins, Elisabeth C. Matthews, J. M. Matthews, Jean-Sébastien Mayer, Stanimir Metchev, Lina Messamah, Leslie Moranta, Dany Mounzer, N. Nari, Louise D. Nielsen, Ares Osborn, Mathieu Ouellet, Jon Otegi, L. Pasquini, V. M. Passegger, Stefan Pelletier, Céline Péroux, Caroline Piaulet, Mykhaylo Plotnykov, E. Pompei, Anne-Sophie Poulin-Girard, José Luis Rasilla, В. А. Решетов, Jonathan Saint-Antoine, Mirsad Sarajlic, I. Saviane, Robin Schnell, Alex Segovia, J. V. Seidel, A. Silber, Peter R. Sinclair, Michaël Sordet, Danuta Sosnowska, Avidaan Srivastava, Atanas K. Stefanov, Márcio A. Teixeira, Simon Thibault, Philippe Vallée, Thomas Vandal, Valentina Vaulato, Joost P. Wardenier, Bachar Wehbé, Drew Weisserman, Ivan Wevers, F. Wildi, Vincent Yariv, G. Zins · 发表于：Astronomy and Astrophysics · 年份：2025 · DOI：10.1051/0004-6361/202555684 · 被引用次数：5 · 研究领域：Stellar, planetary, and galactic studies、Astro and Planetary Science、Astrophysics and Star Formation Studies

Context . The Near InfraRed Planet Searcher (NIRPS) joined HARPS on the 3.6-m ESO telescope at La Silla Observatory in April 2023, dedicating part of its Guaranteed Time Observations (GTO) program to the radial velocity follow-up of TESS planet candidates to confirm and characterize transiting planets around M dwarfs. Aims . We present the “Sub-Neptunes” subprogram of the NIRPS-GTO, aimed at investigating the composition and formation of sub-Neptunes orbiting M dwarfs. We report the first results of this program with the characterization of the TOI-756 system, which consists of TOI-756 b, a transiting sub-Neptune candidate detected by TESS, as well as TOI-756 c, an additional non-transiting planet discovered by NIRPS and HARPS. Methods . We analyzed TESS and ground-based photometry, high-resolution imaging, and high-precision radial velocities (RVs) from NIRPS and HARPS to characterize the two newly discovered planets orbiting TOI-756, as well as to derive the fundamental properties of the host star. A dedicated approach was employed for the NIRPS RV extraction to mitigate telluric contamination, particularly when the star’s systemic velocity was shown to overlap with the barycentric Earth radial velocity. Results . TOI-756 is a M1V-type star with an effective temperature of T eff ~ 3657 K and a super-solar metallicity ([Fe/H]) of 0.20±0.03 dex. TOI-756 b is a 1.24-day period sub-Neptune with a radius of 2.81 ± 0.10 R ⊕ and a mass of 9.8 −1.6 +1.8 M ⊕ . TOI-756 c is a cold ec...