TOI-5344 b: A Saturn-like planet orbiting a super-Solar metallicity M0 dwarf

Abstract

We confirm the planetary nature of TOI-5344 b as a transiting giant exoplanet around an M0 dwarf star. TOI-5344 b was discovered with the Transiting Exoplanet Survey Satellite photometry and confirmed with ground-based photometry (the Red Buttes Observatory 0.6m telescope), radial velocity (the Habitable-zone Planet Finder), and speckle imaging (the NN-Explore Exoplanet Stellar Speckle Imager). TOI-5344 b is a Saturn-like giant planet ($\ddot{I}=0.80_{-0.15}^{+0.17}{\text{g cm}}^{-3}$) with a planetary radius of $9.7\pm 0.5{\text{R}}_{\oplus }$ ($0.87\pm 0.04{\text{R}}_{\text{Jup}}$) and a planetary mass of $135_{-18}^{+17}{\text{M}}_{\oplus }$ ($0.42_{-0.06}^{+0.05}{\text{M}}_{\text{Jup}}$). It has an orbital period of $3.792622\pm 0.000010$ days and an orbital eccentricity of $0.06_{-0.04}^{+0.07}$. We measure a high metallicity for TOI-5344 of [Fe/H] = $0.48\pm 0.12$, where the high metallicity is consistent with expectations from formation through core accretion. We compare the metallicity of the M-dwarf hosts of giant exoplanets to that of M-dwarf hosts of non-giants ($\lesssim 8{\text{R}}_{\oplus }$). While the two populations appear to show different metallicity distributions, quantitative tests are prohibited by various sample caveats.

19 pages, 10 figures, 4 tables, AJ accepted. Added references