Radial velocity detection of the TRAPPIST-1 planetary system with SPIRou and NIRPS
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 (Δln𝒵=7.53, 1860:1 odds) the combined RV signature of the planets by informing their relative masses on the TTV analysis, with TRAPPIST-1 b as a proxy of the whole system. For the first time, the RV signal of the TRAPPIST-1 system is recovered: we find a RV semi-amplitude of Kb=3.65+0.78−0.83 m s−1 corresponding to a planetary mass of Mp, b=1.31±0.29 M⊕, demonstrating that the RV measurements are consistent with the TTV model (Mp, 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+0.22−0.20 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, placing an upper limit on the longitudinal field (|Bl|<40 G, 3σ). This limit is compatible with a weak multipolar large-scale magnetic geometry, as observed in some of the later-type rapidly rotating M dwarfs.
Related
- The GAPS programme at TNG. LXXIX. New mass constraints for the infant planets in the V1298,Tau system through a long-term radial-velocity monitoring with HARPS-N
- Exoplanet Detection Techniques: Radial Velocity
- Radial Velocity Evidence for a Post-mass-transfer Massive Binary System NaSt1
- The GAPS programme at TNG LXXIX. New mass constraints for the infant planets in the V1298 Tau system through a long-term radial velocity monitoring with HARPS-N
- VELOcities of CEpheids (VELOCE) III. Reconstructing radial velocity curves of classical Cepheids
BibTeX
@misc{lheureux2026radial,
title = {{Radial velocity detection of the TRAPPIST-1 planetary system with SPIRou and NIRPS}},
author = {Alexandrine L'Heureux and René Doyon and Charles Cadieux and Pascal Petit and Olivia Lim and Étienne Artigau and Neil J. Cook and Eric Agol and Xavier Bonfils and Julien Morin and Stefano Bellotti and Claire Moutou and Leslie Moranta and Jean-François Donati and Luc Arnold and Xavier Delfosse and Guillaume Hébrard and Romain Allart and François Bouchy and Lucile Mignon and Izan de Castro Leão and Dany Mounzer and Khaled Al Moulla and Frédérique Baron and Björn Benneke and Mathis Bouffard and Casey Brinkman and Bruno L. Canto Martins and Andres Carmona and Ryan Cloutier and Marion Cointepas and Nicolas B. Cowan and Eduardo Cristo and Roseane de Lima Gomes and Jose Renan De Medeiros and Xavier Dumusque and Dasaev O. Fontinele and Thierry Forveille and Yolanda G. C. Frensch and Jonathan Gagné and Jonay I. González Hernández and Nicole Gromek and Melissa J. Hobson and Vigneshwaran Krishnamurthy and Pierrot Lamontagne and Lison Malo and Eder Martioli and Yuri S. Messias and Louise D. Nielsen and Ares Osborn and Léna Parc and Caroline Piaulet-Ghorayeb and Nuno C. Santos and Bennett Neil Skinner and Avidaan Srivastava and Atanas K. Stefanov and Alejandro Suárez Mascareño and Gregg Wade and Joost P. Wardenier and Drew Weisserman},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.03006},
eprint = {2609.03006},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.03006},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Radial velocity detection of the TRAPPIST-1 planetary system with SPIRou and NIRPS
AU - Alexandrine L'Heureux
AU - René Doyon
AU - Charles Cadieux
AU - Pascal Petit
AU - Olivia Lim
AU - Étienne Artigau
AU - Neil J. Cook
AU - Eric Agol
AU - Xavier Bonfils
AU - Julien Morin
AU - Stefano Bellotti
AU - Claire Moutou
AU - Leslie Moranta
AU - Jean-François Donati
AU - Luc Arnold
AU - Xavier Delfosse
AU - Guillaume Hébrard
AU - Romain Allart
AU - François Bouchy
AU - Lucile Mignon
AU - Izan de Castro Leão
AU - Dany Mounzer
AU - Khaled Al Moulla
AU - Frédérique Baron
AU - Björn Benneke
AU - Mathis Bouffard
AU - Casey Brinkman
AU - Bruno L. Canto Martins
AU - Andres Carmona
AU - Ryan Cloutier
AU - Marion Cointepas
AU - Nicolas B. Cowan
AU - Eduardo Cristo
AU - Roseane de Lima Gomes
AU - Jose Renan De Medeiros
AU - Xavier Dumusque
AU - Dasaev O. Fontinele
AU - Thierry Forveille
AU - Yolanda G. C. Frensch
AU - Jonathan Gagné
AU - Jonay I. González Hernández
AU - Nicole Gromek
AU - Melissa J. Hobson
AU - Vigneshwaran Krishnamurthy
AU - Pierrot Lamontagne
AU - Lison Malo
AU - Eder Martioli
AU - Yuri S. Messias
AU - Louise D. Nielsen
AU - Ares Osborn
AU - Léna Parc
AU - Caroline Piaulet-Ghorayeb
AU - Nuno C. Santos
AU - Bennett Neil Skinner
AU - Avidaan Srivastava
AU - Atanas K. Stefanov
AU - Alejandro Suárez Mascareño
AU - Gregg Wade
AU - Joost P. Wardenier
AU - Drew Weisserman
PY - 2026
DA - 2026/09/02
PB - arXiv
DO - 10.48550/arxiv.2609.03006
UR - https://arxiv.org/abs/2609.03006
AB - 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 (Δln𝒵=7.53, 1860:1 odds) the combined RV signature of the planets by informing their relative masses on the TTV analysis, with TRAPPIST-1 b as a proxy of 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^+0.78_−0.83 m s^−1 corresponding to a planetary mass of M_p, b=1.31±0.29 M_⊕, demonstrating 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^+0.22_−0.20 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, placing an upper limit on the longitudinal field (|B_l|<40 G, 3σ). This limit is compatible with a weak multipolar large-scale magnetic geometry, as observed in some of the later-type rapidly rotating M dwarfs.
ER -