| Issue |
A&A
Volume 688, August 2024
|
|
|---|---|---|
| Article Number | A196 | |
| Number of page(s) | 16 | |
| Section | Planets and planetary systems | |
| DOI | https://doi.org/10.1051/0004-6361/202450466 | |
| Published online | 22 August 2024 | |
Characterising planetary systems with SPIRou: Temperate sub-Neptune exoplanet orbiting the nearby fully convective star GJ 1289 and a candidate around GJ 3378★,★★
1
Univ. de Toulouse, CNRS, IRAP,
14 avenue Belin,
31400
Toulouse,
France
e-mail: claire.moutou@irap.omp.eu
2
Institut Trottier de Recherche sur les Exoplanètes, Université de Montréal,
1375 Ave Thérèse-Lavoie-Roux,
Montréal,
QC
H2V 0B3,
Canada
3
Univ. Grenoble Alpes, CNRS, IPAG,
38000
Grenoble,
France
4
Canada-France-Hawaii Telescope, CNRS,
96743
Kamuela,
Hawaii,
USA
5
Aix-Marseille Université, CNRS, CNES, LAM (Laboratoire d'Astrophysique de Marseille),
Marseille,
France
6
Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie,
98 bis boulevard Arago,
75014
Paris,
France
Received:
22
April
2024
Accepted:
10
June
2024
We report the discovery of two new exoplanet systems around fully convective stars, found from the radial-velocity (RV) variations of their host stars measured with the nIR spectropolarimeter CFHT/SPIRou over multiple years. GJ 3378 b is a planet with minimum mass of 5.26−0.97+0.94 M⊕ on an eccentric 24.73-day orbit around an M4V star of 0.26 M⊙. GJ 1289 b has a minimum mass of 6.27 ± 1.25 M⊙ in a 111.74-day orbit, on a circular orbit around an M4.5V star of mass 0.21 M⊙. Both stars are in the solar neighbourhood, at 7.73 and 8.86 pc, respectively. The low-amplitude RV signals are detected after line-by-line post-processing treatment. These potential sub-Neptune class planets around cool stars may have temperate atmospheres and be interesting nearby systems for further studies. We also recovered the large-scale magnetic field of both stars, found to be mostly axisymmetric and dipolar, with polar strengths of 20–30 G and 200–240 G for GJ 3378 (in 2019–2021) and GJ 1289 (in 2022–2023), respectively. The rotation periods measured with the magnetic field differ from the orbital periods and, in general, stellar activity is not seen in the studied nIR RV time series of both stars. GJ 3378 b detections have not been confirmed by optical RVs and, therefore, they are solely considered a candidate for the present purposes.
Key words: instrumentation: spectrographs / techniques: radial velocities / stars: magnetic field / planetary systems / stars: individual: GJ 1289 / stars: individual: GJ 3378
Radial velocity tables are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/688/A196
Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. The observations at the CFHT were performed with care and respect from the summit of Maunakea which is a significant cultural and historic site.
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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