TOI-1759 b: A transiting sub-Neptune around a low mass star characterized with SPIRou and TESS

Creators: Martioli, E.; Hébrard, G.; Fouqué, P.; Artigau, É.; Donati, J.-F.; Cadieux, C.; Bellotti, S.; Lecavelier des Etangs, A.; Doyon, R.; do Nascimento, J.-D.; Arnold, L.; Carmona, A.; Cook, N. J.; Cortes-Zuleta, P.; de Almeida, L.; Delfosse, X.; Folsom, C. P.; König, P.-C.; Moutou, C.; Ould-Elhkim, M.; Petit, P.; Stassun, K. G.; Vidotto, A. A.; Vandal, T.; Benneke, B.; Boisse, I.; Bonfils, X.; Boyd, P.; Brasseur, C.; Charbonneau, D.; Cloutier, R.; Collins, K.; Cristofari, P.; Crossfield, I.; Díaz, R. F.; Fausnaugh, M.; Figueira, P.; Forveille, T.; Furlan, E.; Girardin, E.; Gnilka, C. L.; Gomes da Silva, J.; Gu, P.-G.; Guerra, P.; Howell, S. B.; Hussain, G. A. J.; Jenkins, J. M.; Kiefer, F.; Latham, D. W.; Matson, R. A.; Matthews, E. C.; Morin, J.; Naves, R.; Ricker, G.; Seager, S.; Takami, M.; Twicken, J. D.; Vanderburg, A.; Vanderspek, R.; Winn, J.

Abstract

We report the detection and characterization of the transiting sub-Neptune TOI-1759 b, using photometric time series from the Transiting Exoplanet Survey Satellite (TESS) and near-infrared spectropolarimetric data from the Spectro-Polarimètre Infra Rouge (SPIRou) on the Canada-France-Hawaii Telescope. TOI-1759 b orbits a moderately active M0V star with an orbital period of 18.849975 ± 0.000006 days, and we measured a planetary radius and mass of 3.06 ± 0.22 R⊕ and 6.8 ± 2.0 M⊕. Radial velocities were extracted from the SPIRou spectra using both the cross-correlation function and the line-by-line methods, optimizing the velocity measurements in the near-infrared domain. We analyzed the broadband spectral energy distribution of the star and the high-resolution SPIRou spectra to constrain the stellar parameters and thus improve the accuracy of the derived planet parameters. A least squares deconvolution analysis of the SPIRou Stokes V polarized spectra detects Zeeman signatures in TOI-1759. We modeled the rotational modulation of the magnetic stellar activity using a Gaussian process regression with a quasi-periodic covariance function and find a rotation period of 35.65_(−0.15)^(+0.17) days. We reconstructed the large-scale surface magnetic field of the star using Zeeman-Doppler imaging, which gives a predominantly poloidal field with a mean strength of 18 ± 4 G. Finally, we performed a joint Bayesian Markov chain Monte Carlo analysis of the TESS photometry and SPIRou radial velocities to optimally constrain the system parameters. At 0.1176 ± 0.0013 au from the star, the planet receives 6.4 times the bolometric flux incident on Earth, and its equilibrium temperature is estimated at 433 ± 14 K. TOI-1759 b is a likely gas-dominated sub-Neptune with an expected high rate of photoevaporation. Therefore, it is an interesting target to search for neutral hydrogen escape, which may provide important constraints on the planetary formation mechanisms responsible for the observed sub-Neptune radius desert.

Additional Information

© E. Martioli et al. 2022. 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. Received 28 October 2021; Accepted 2 February 2022; Published online 20 April 2022. Based on observations obtained at the Canada–France–Hawaii Telescope (CFHT), which is operated from the summit of Maunakea by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. Based on observations obtained with SPIRou, an international project led by Institut de Recherche en Astrophysique et Planétologie, Toulouse, France. We acknowledge funding from the French National Research Agency (ANR) under contract number ANR18CE310019 (SPlaSH). This work is supported by the ANR in the framework of the Investissements d'Avenir program (ANR-15-IDEX-02), through the funding of the "Origin of Life" project of the Grenoble-Alpes University. T.V. and C.C. acknowledge funding from the Technologies for Exo-Planetary Science (TEPS) CREATE program and from the Fonds de Recherche du Quebec - Nature et technologies. J.F.D. acknowledges funding from the European Research Council (ERC) under the H2020 research & innovation programme (grant agreements 740651 New Worlds). A.A.V. acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 817540, ASTROFLOW). This paper includes data collected with the TESS mission, obtained from the MAST data archive at the Space Telescope Science Institute (STScI). We acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. Some of the observations in the paper made use of the High-Resolution Imaging instrument 'Alopeke. 'Alopeke was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. Data were reduced using a software pipeline originally written by Elliott Horch and Mark Everett. 'Alopeke was mounted on the Gemini North telescope of the international Gemini Observatory, a program of NSF's OIR Lab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnolog'ia e Innovación (Argentina), Ministério da Ciência, Tec-nologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea).

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