TOI-530b: a giant planet transiting an M-dwarf detected by <i>TESS</i>
Tianjun Gan, Zitao Lin, Sharon X. Wang, Shude Mao, P. Fouqué, Jiahao Fan, Megan Bedell, Keivan G. Stassun, Steven Giacalone, Akihiko Fukui, F. Murgas, David R. Ciardi, Steve B. Howell, Karen A. Collins, Avi Shporer, L. Arnold, Thomas Barclay, David Charbonneau, Jessie L. Christiansen, Ian J. M. Crossfield, Courtney D. Dressing, Ashley Elliott, E. 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, H. Parviainen, Benjamin V. Rackham, David R. Rodriguez, Mark E. Rose, Alexander Rudat, Joshua E. Schlieder, Nicholas J. Scott, M. Vezie, G. Ricker, R. Vanderspek, David W. Latham, Sara Seager, Joshua N. Winn, Jon M. Jenkins
Abstract
ABSTRACT 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 RJ and a mass of 0.37 ± 0.08 MJ 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.