TOI-3288 b and TOI-4666 b: Two gas giants transiting low-mass stars characterised by NIRPS

@article{frensch2026toi3288,
  title = {{TOI-3288 b and TOI-4666 b: Two gas giants transiting low-mass stars characterised by NIRPS}},
  author = {Yolanda Frensch and François Bouchy and Gaspare Lo Curto and Alexandrine L’heureux and Roseane de Lima Gomes and João Faria and Xavier Dumusque and Lison Malo and Marion Cointepas and Avidaan Srivastava and Xavier Bonfils and Elisa Delgado-Mena and Nicola Nari and Étienne Artigau and Frédérique Baron and Susana Barros and Björn Benneke and Marta Bryan and Bruno Canto Martins and Izan de Castro Leão and Ryan Cloutier and Neil Cook and Nicolas Cowan and Eduardo Cristo and Jose de Medeiros and Xavier Delfosse and René Doyon and David Ehrenreich and Jonay González Hernández and David Lafrenière and Christophe Lovis and Claudio Melo and Lucile Mignon and Christoph Mordasini and Francesco Pepe and Rafael Rebolo and Jason Rowe and Nuno Santos and Damien Ségransan and Alejandro Suárez Mascareño and Stéphane Udry and Diana Valencia and Gregg Wade and Khaled Al Moulla and Romain Allart and Jose Almenara and Khalid Barkaoui and Charles Cadieux and Amadeo Castro-González and Karen Collins and Sergio Fajardo-Acosta and Thierry Forveille and Tianjun Gan and João Gomes da Silva and Nolan Grieves and Melissa Hobson and Steve Howell and Pierrot Lamontagne and Lina Messamah and Louise Nielsen},
  journal = {Astronomy \& Astrophysics - A\&A},
  year = {2026},
  month = oct,
  doi = {10.1051/0004-6361/202557656},
  eprint = {2510.11703},
  archivePrefix = {arXiv},
  url = {https://hal.science/hal-05843507v1},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - TOI-3288 b and TOI-4666 b: Two gas giants transiting low-mass stars characterised by NIRPS
AU  - Yolanda Frensch
AU  - François Bouchy
AU  - Gaspare Lo Curto
AU  - Alexandrine L’heureux
AU  - Roseane de Lima Gomes
AU  - João Faria
AU  - Xavier Dumusque
AU  - Lison Malo
AU  - Marion Cointepas
AU  - Avidaan Srivastava
AU  - Xavier Bonfils
AU  - Elisa Delgado-Mena
AU  - Nicola Nari
AU  - Étienne Artigau
AU  - Frédérique Baron
AU  - Susana Barros
AU  - Björn Benneke
AU  - Marta Bryan
AU  - Bruno Canto Martins
AU  - Izan de Castro Leão
AU  - Ryan Cloutier
AU  - Neil Cook
AU  - Nicolas Cowan
AU  - Eduardo Cristo
AU  - Jose de Medeiros
AU  - Xavier Delfosse
AU  - René Doyon
AU  - David Ehrenreich
AU  - Jonay González Hernández
AU  - David Lafrenière
AU  - Christophe Lovis
AU  - Claudio Melo
AU  - Lucile Mignon
AU  - Christoph Mordasini
AU  - Francesco Pepe
AU  - Rafael Rebolo
AU  - Jason Rowe
AU  - Nuno Santos
AU  - Damien Ségransan
AU  - Alejandro Suárez Mascareño
AU  - Stéphane Udry
AU  - Diana Valencia
AU  - Gregg Wade
AU  - Khaled Al Moulla
AU  - Romain Allart
AU  - Jose Almenara
AU  - Khalid Barkaoui
AU  - Charles Cadieux
AU  - Amadeo Castro-González
AU  - Karen Collins
AU  - Sergio Fajardo-Acosta
AU  - Thierry Forveille
AU  - Tianjun Gan
AU  - João Gomes da Silva
AU  - Nolan Grieves
AU  - Melissa Hobson
AU  - Steve Howell
AU  - Pierrot Lamontagne
AU  - Lina Messamah
AU  - Louise Nielsen
PY  - 2026
DA  - 2026/10/29
JO  - Astronomy & Astrophysics - A&A
DO  - 10.1051/0004-6361/202557656
UR  - https://hal.science/hal-05843507v1
AB  - Context. Gas giant planets orbiting low-mass stars (T eff ≲ 4600 K) are uncommon outcomes of planet formation. Increasing the sample of wellcharacterised giants around early M dwarfs will enable population-level studies of their properties, offering valuable insights into their formation and evolutionary histories. Aims. We aim to confirm and characterise giant exoplanets transiting M dwarfs identified by the TESS mission. To this end, we have started the Gas giAnts Transiting lOw-mass Stars (GATOS) program within the NIRPS Guaranteed Time Observations (GTO). Methods. High-resolution spectroscopic data are obtained in the optical and near-infrared (nIR), combining HARPS and NIRPS. We derive radial velocities (RVs) via the cross-correlation function and implement a novel post-processing procedure to further mitigate telluric contamination in the nIR. The resulting RVs are jointly fit with TESS and ground-based photometry to derive the orbital and physical parameters of the systems. Results. We present the GATOS program and its first results. We confirm two gas giants transiting the low-mass stars TOI-3288 A (K9V, T eff = 3933 ± 48 K) and TOI-4666 (M2.5V, T eff = 3512 ± 36 K). TOI-3288 A hosts a Hot Jupiter with a mass of 2.11 ± 0.08 M Jup and a radius of 1.00 ± 0.03 R Jup , with an orbital period of 1.43 days (T eq = 1059 ± 20 K). TOI-4666 hosts a 0.70 ± 0.06 M Jup warm Jupiter (T eq = 713 ± 14 K) with a radius of 1.11 ± 0.04 R Jup , with an orbital period of 2.91 days. At a population level, we identify a decrease in planetary mass with spectral type, where late M dwarfs host less massive giant planets than early M dwarfs. More massive gas giants that deviate from this trend are preferentially hosted by more metal-rich stars. Furthermore, we find an increased binarity fraction among low-mass stars hosting gas giants, which may play a role in enhancing giant planet formation around low-mass stars. Conclusions. These mass characterizations contribute to the growing catalogue of well-defined giant exoplanets around low-mass stars. The observed population trends agree with theoretical predictions, where higher metallicity can compensate for lower disk masses, and wide binary systems may influence planet formation and migration through Kozai-Lidov cycles or disk instabilities.
SN  - 0004-6361
SN  - 1432-0746
ER  -