Characterizing planetary systems with SPIRou: Detection of a sub-Neptune in a 6-day period orbit around the M dwarf Gl 410^★

¹ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
² Univ. de Toulouse, CNRS, IRAP, 14 avenue Belin, 31400 Toulouse, France
³ SUPA School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK
⁴ Aix Marseille Université, CNRS, CNES, Institut Origines, LAM, Marseille, France
⁵ Trottier Institute for Research on Exoplanets, Université de Montréal, Département de Physique, C.P. 6128 Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
⁶ Observatoire du Mont-Mégantic, Université de Montréal, Département de Physique, C.P. 6128 Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
⁷ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France
⁸ Planétarium de Montréal, Espace pour la Vie, 4801 av. Pierre-de Coubertin, Montréal, Québec, Canada
⁹ Instituto Tecnolόgico de Buenos Aires (ITBA), Buenos Aires C1437, Argentina
¹⁰ International Center for Advanced Studies and ICIFI (CONICET), ECyT-UNSAM, Campus Miguelete, 25 de Mayo y Francia, 1650 Buenos Aires, Argentina
¹¹ Laboratόrio Nacional de Astrofísica, Rua Estados Unidos 154, 37504-364, Itajubá, MG, Brazil
¹² Institut d’astrophysique de Paris, CNRS, UMR 7095, Sorbonne Université, 98 bis bd Arago, 75014 Paris, France
¹³ Canada France Hawaii Telescope Corporation (CFHT), UAR2208 CNRS-INSU, 65-1238 Mamalahoa Hwy, Kamuela, HI 96743, USA
¹⁴ Université de Montpellier, CNRS, LUPM, 34095 Montpellier, France
¹⁵ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹⁶ Center for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
¹⁷ Dep. de Física, Univ. Federal do Rio Grande do Norte – UFRN, Natal, RN 59078-970, Brazil
¹⁸ Department of Physics & Astronomy, McMaster University, 1280 Main St West, Hamilton, ON L8S 4L8, Canada
¹⁹ Departamento de Matemática y Física Aplicadas, Universidad Catόlica de la Santísima Conceptiόn, Alonso de Rivera 2850 Conceptiόn, Chile
²⁰ Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51b, 1290 Versoix, Switzerland
²¹ Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du Six-Août 19C, 4000 Liège, Belgium

^★★ Corresponding author: andres.carmona.astronomy@gmail.com

Received: 7 October 2024
Accepted: 4 April 2025

Abstract

Context. The search for exoplanets around nearby M dwarfs represents a crucial milestone in the census of planetary systems in the vicinity of our Solar System.

Aims. Since 2018 our team has been conducting a blind search program for planets around nearby M dwarfs with the near-IR spectro-polarimeter and velocimeter SPIRou at the Canada-France-Hawaii Telescope and with the optical velocimeter SOPHIE at the Haute-Provence Observatory in France. The aim of this paper is to present our results on Gl 410, a 0.55 M_⊙ 480 ± 150 Myr old active M dwarf distant 12 pc.

Methods. We searched for planetary companions using radial velocities (RVs). We used the line-by-line (LBL) technique to measure the RVs with SPIRou and the template matching method with SOPHIE. Three different methods were employed, two based on principal component analysis (PCA), to clean the SPIRou RVs for systematics. We applied Gaussian processes (GP) modeling to correct the SOPHIE RVs for stellar activity. The ℓ₁ and apodized sine periodogram analysis was used to search for planetary signals in the SPIRou data taking into account activity indicators. We analyzed TESS data and searched for planetary transits.

Results. We report the detection of a M sin(i) = 8.4 ± 1.3 M_⊕ sub-Neptune planet at a period of 6.020 ± 0.004 days in circular orbit with SPIRou. The same signal, although with lower significance, was also retrieved in the SOPHIE RV data after correction for activity using a GP trained on SPIRou’s longitudinal magnetic field (B_ℓ) measurements. The TESS data indicate that the planet is not transiting. Within the SPIRou wPCA RVs, we find tentative evidence for two additional planetary signals at 2.99 and 18.7 days.

Conclusions. Infrared RVs are a powerful method to detect extrasolar planets around active M dwarfs. Care should be taken, however, to correct or filter systematics generated by residuals of the telluric correction or small structures in the detector plane. The LBL technique combined with PCA offers a promising way to reach this objective. Further monitoring of Gl 410 is necessary.