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

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-circle dot and a mass of M-* = 0.53 +/- 0.02 M-circle dot. 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 x 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.

Automated summary

We report the discovery of TOI-530b, a Saturn-like planet orbiting an M0.5V dwarf star. Through various measurements and analysis, we confirmed the nature of this planet and its relationship with the host star. The findings contribute to the understanding of planet formation and migration around M-type stars.