Homogeneous search for helium in the atmosphere of 11 gas giant exoplanets with SPIRou

¹ Département de Physique, Institut Trottier de Recherche sur les Exoplanètes, Université de Montréal, Montréal, Québec H3T 1J4, Canada
e-mail: romain.allart@umontreal.ca
² Observatoire astronomique de l’Université de Genève, Université de Genève, chemin Pegasi 51, 1290 Versoix, Switzerland
³ Gemini Observatory, NSF’s NOIRLab, Casilla 603, La Serena, Chile
⁴ Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
⁵ Dept. of Physics & Astronomy, McMaster University, 1280 Main St West, Hamilton, ON L8S 4L8, Canada
⁶ Department of Physics, McGill University, 3600 rue University, Montréal, QC H3A 2T8, Canada
⁷ Department of Earth & Planetary Sciences, McGill University, 3450 rue University, Montréal, QC H3A 0E8, Canada
⁸ Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, 14 avenue Édouard Belin, 31400, Toulouse, France
⁹ Department of Earth Sciences, University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
¹⁰ Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan
¹¹ Institut d’Astrophysique de Paris, CNRS, UMR 7095, Sorbonne Université, 98 bis bd Arago, 75014 Paris, France
¹² Observatoire de Haute-Provence, 1912 Route de l’Observatoire, 04870 St Michel l’Observatoire, France
¹³ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 5 place Jules Janssen, 92195 Meudon, France
¹⁴ Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Eötvös Loránd Research Network (ELKH), Konkoly- Thege Miklós út 15–17, 1121 Budapest, Hungary
¹⁵ CSFK, MTA Centre of Excellence, Konkoly-Thege Miklós út 15–17, 1121 Budapest, Hungary
¹⁶ ELTE Eötvös Loránd University, Institute of Physics, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary
¹⁷ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
¹⁸ Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
¹⁹ Laboratório Nacional de Astrofísica, Rua Estados Unidos 154, Itajubá, MG 37504364, Brazil
²⁰ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
²¹ Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan
²² Department of Astronomy and Carl Sagan Institute, Cornell University, 122 Sciences Drive, Ithaca, NY 14853, USA
²³ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

Received: 31 December 2022
Accepted: 22 June 2023

Abstract

The metastable helium triplet in the near-infrared (10 833 Å) is among the most important probes of exoplanet atmospheres. It can trace their extended outer layers and constrain mass loss. We used the near-infrared high-resolution spectropolarimeter SPIRou on the CFHT to search for the spectrally resolved helium triplet in the atmospheres of eleven exoplanets, ranging from warm mini-Neptunes to hot Jupiters and orbiting G, K, and M dwarfs. Observations were obtained as part of the SPIRou Legacy Survey and complementary open-time programs. We applied a homogeneous data reduction to all datasets and set constraints on the presence of metastable helium, despite the presence of systematics in the data. We confirm published detections for HAT-P-11 b, HD 189733 b, and WASP-69 b and set upper limits for the other planets. We applied the p–winds open source code to set upper limits on the mass-loss rate for the nondetections and to constrain the thermosphere temperature, mass-loss rate, line-of-sight velocity, and the altitude of the thermosphere for the detections. We confirm that the presence of metastable helium correlates with the stellar mass and the extreme-ultraviolet flux received by the planets. We investigated the correlation between the mass-loss rate and the presence of metastable helium, but it remains difficult to draw definitive conclusions. Finally, some of our results are in contradiction with previous results in the literature, and therefore we stress the importance of repeatable, homogeneous, and larger-scale analyses of the helium triplet to obtain robust statistics, study temporal variability, and better understand how the helium triplet can be used to explore the evolution of exoplanets.