Radial velocity detection of the TRAPPIST-1 planetary system with SPIRou and NIRPS
Year: 2026
Type: article
Abstract: The TRAPPIST-1 system is well known for its seven transiting Earth-sized exoplanets. It has been extensively studied and characterized, notably with transit timing variations (TTVs), to precisely measure the mass of the planets. Using near-infrared spectroscopic observations obtained as part of the SPIRou Legacy Survey and the NIRPS Guaranteed Time Observation programs, we aimed to verify those values through radial velocity (RV) measurements of the system. Our RV analysis reveals that the current data do not have the precision required to individually detect the TRAPPIST-1 planets. However, we confidently detect (Δ ln 𝒵 = 7.53, 1860:1 odds) the combined RV signature of the planets by using the relative masses derived from the TTV analysis, with TRAPPIST-1 b as a proxy for the whole system. For the first time, the RV signal of the TRAPPIST-1 system is recovered: we find a RV semi-amplitude of K b = 3.65 −0.83 +0.78 m s −1 . This corresponds to a planetary mass of M p , b = 1.31 ± 0.29 M ⊕ and demonstrates that the RV measurements are consistent with the TTV model ( M p , b; TTV = 1.374 ± 0.069 M ⊕ ). Additionally, the NIRPS RVs constrain the presence of giant planets beyond the snow line, excluding Saturn-mass planets out to 2.7-yr orbits and Neptune-mass objects out to 20 d. Through RV, we determined the stellar activity period to be of 3.22 −0.20 +0.22 d. Its agreement with photometric measurements (K2 and TESS) confirms stellar rotation as the origin of the ~3.3-d periodicity observed for TRAPPIST-1. We further investigated stellar activity with SPIRou polarimetric measurements, and placed an upper limit on the longitudinal field (| B l | < 40 G, 3 σ ). This limit is compatible with a weak multipolar large-scale magnetic geometry, as observed in some of the later-type rapidly rotating M dwarfs.
Source: Astronomy and Astrophysics
Authors: Alexandrine L’Heureux, René Doyon, Charles Cadieux, Pascal Petit, Olivia Lim, Étienne Artigau, Neil J. Cook, Eric Agol, Xavier Bonfils, Julien Morin, Stefano Bellotti, Claire Moutou, Leslie Moranta, Jean-François Donati, Luc Arnold, Xavier Delfosse, Guillaume Hébrard, Romain Allart, François Bouchy, Lucile Mignon, Izan de Castro Leão, Dany Mounzer, Khaled Al Moulla, Frédérique Baron, Björn Benneke, Mathis Bouffard, Casey Brinkman, Bruno L. Canto Martins, Andrés Carmona, Ryan Cloutier, Marion Cointepas, Nicolas B. Cowan, Eduardo Cristo, Roseane de Lima Gomes, José Renan De Medeiros, Xavier Dumusque, Dasaev O. Fontinele, Thierry Forveille, Yolanda G. C. Frensch, Jonathan Gagné, Jonay I. González Hernández, Nicole Gromek, Melissa J. Hobson, Vigneshwaran Krishnamurthy, Pierrot Lamontagne, Lison Malo, Eder Martioli, Yuri S. Messias, Louise D. Nielsen, Ares Osborn, Léna Parc, Caroline Piaulet-Ghorayeb, Nuno C. Santos, Bennett Neil Skinner, Avidaan Srivastava, Atanas K. Stefanov, Alejandro Suárez Mascareño, Gregg Wade, Joost P. Wardenier, Drew Weisserman
Institutions: Université de Montréal, University of Geneva, Centre National de la Recherche Scientifique, Observatoire Midi-Pyrénées, Université de Toulouse, University of Washington, Institut de Planétologie et d'Astrophysique de Grenoble, Université Grenoble Alpes, Université de Montpellier, Laboratoire Univers et Particules de Montpellier, Leiden University, Leiden Observatory, Espace pour la vie, Canada–France–Hawaii Telescope, Institut d'Astrophysique de Paris, Sorbonne Université, Universidade Federal do Rio Grande do Norte, Universidade do Porto, Institute of Astrophysics and Space Sciences, Centro de Astrofísica da Universidade do Porto, McGill University, McMaster University, Universidad de La Laguna, Instituto de Astrofísica de Canarias, Consejo Superior de Investigaciones Científicas, Instituto de Astrofísica de Andalucía, Laboratório Nacional de Astrofísica, European Southern Observatory, European Southern Observatory, Ludwig-Maximilians-Universität München, University of Warwick, University of Chicago, Queen's University, Royal Military College of Canada, University of Bern
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Funders: National Science Foundation, National Aeronautics and Space Administration, Université Laval, University of Hawai'i, Ministère de l'Économie, de l’Innovation et des Exportations du Québec, Space Telescope Science Institute, Indian Council of Agricultural Research, Agence Nationale de la Recherche, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Centre National de la Recherche Scientifique, Université de Montréal, Ames Research Center, Horizon 2020 Framework Programme, Science Mission Directorate, Natural Sciences and Engineering Research Council of Canada, Fonds de recherche du Québec – Nature et technologies, Institut national des sciences de l'Univers
Awards: G155371794, G2121614283, G2171960263, G292453335, G3126238791, G4127404903, Phasenübergänge und Instabilitäten, G4276578120, G433322167, G4518818167, G4596981220, Bourses de maîtrise en recherche — Systèmes planétaire et solaire, G5753977096, G58316358, G6273510985, G767601387, G8210229802, G8318038168, G8438684293, G8964069747
OpenAlex ID: W7208788542