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

Abstract

We report the discovery of TOI-530b, a transiting giant 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 multi-wavelength 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 0.4 ± 0.1 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. We discuss the potential formation channel of such systems.

TOI-3757 b: A low density gas giant orbiting a solar-metallicity M dwarf

“…Assuming that the progenitor protoplanetary disk had the same metallicity as the host star, the disk for TOI-3757 is ∼ 0.3 dex poorer in metallicity compared to the median metallicity of the other transiting gas giants around M dwarfs (Figure 10b). Gan et al (2021) discuss the metallicity trends seen in the transiting M dwarf Jovian sample, which have a median metallicity of ∼ 0.3 dex, when the sample is updated to include the Jovian planets that have been confirmed since. This directly influences the formation of the 14 Refer to Passegger et al (2022) for a detailed discussion on the caveats and challenges associated with estimating M dwarf metallicities.…”