TOI-530b: a giant planet transiting an M-dwarf detected by TESS

Tianjun Gan , Zitao Lin , Sharon Xuesong Wang , Shude Mao , Pascal Fouqué (1, 2) , Jiahao Fan , Megan Bedell , Keivan G. Stassun , Steven Giacalone , Akihiko Fukui , Felipe Murgas , David R. Ciardi , Steve B. Howell , Karen A. Collins , Avi Shporer , Luc Arnold (1) , Thomas Barclay , David Charbonneau , Jessie Christiansen , Ian J. M. Crossfield , Courtney D. Dressing , Ashley Elliott , Emma Esparza-Borges , Phil Evans , Crystal L. Gnilka , Erica J. Gonzales , Andrew W. Howard , Keisuke Isogai , Kiyoe Kawauchi , Seiya Kurita , Beibei Liu , John H. Livingston , Rachel A. Matson , Norio Narita , Enric Palle , Hannu Parviainen , Benjamin V. Rackham , David R. Rodriguez , Mark Rose , Alexander Rudat , Joshua E. Schlieder , Nicholas J. Scott , Michael Vezie , George R. Ricker , Roland Vanderspek , David W. Latham , Sara Seager , Joshua N. Winn , Jon M. Jenkins

1 CFHT - Canada-France-Hawaii Telescope Corporation
2 IRAP - Institut de recherche en astrophysique et planétologie

We report the discovery of TOI-530b, a transiting Saturn-like planet around an M0.5V dwarf, delivered by the Transiting Exoplanet Survey Satellite (TESS). The host star is located at a distance of 147.7 ± 0.6 pc with a radius of R_* = 0.54 ± 0.03 R_⊙ and a mass of M_* = 0.53 ± 0.02 M_⊙. We verify the planetary nature of the transit signals by combining ground-based multiwavelength photometry, high-resolution spectroscopy from SPIRou as well as high-angular-resolution imaging. With V = 15.4 mag, TOI-530b is orbiting one of the faintest stars accessible by ground-based spectroscopy. Our model reveals that TOI-530b has a radius of 0.83 ± 0.05 R_J and a mass of 0.37 ± 0.08 M_J on a 6.39-d orbit. TOI-530b is the sixth transiting giant planet hosted by an M-type star, which is predicted to be infrequent according to core accretion theory, making it a valuable object to further study the formation and migration history of similar planets. Furthermore, we identify a potential dearth of hot massive giant planets around M-dwarfs with separation distance smaller than 0.1 au and planet-to-star mass ratio between 2 × 10^-3 and 10^-2. We also find a possible correlation between hot giant planet formation and the metallicity of its parent M-dwarf. We discuss the potential formation channel of such systems.

Keywords: planets and satellites: detection; planets and satellites: gaseous planets; planets and satellites: individual: TIC 387690507; TOI 530; stars: low-mass; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics

Domains: Sciences of the Universe [physics]

Tianjun Gan, Zitao Lin, Sharon Xuesong Wang, Shude Mao, Pascal Fouqué, et al.. TOI-530b: a giant planet transiting an M-dwarf detected by TESS. Monthly Notices of the Royal Astronomical Society, 2022, 511, pp.83-99. ⟨10.1093/mnras/stab3708⟩. ⟨insu-03672039⟩