Searching for GEMS: TOI-5349b is a Saturn-like planet orbiting a metal-rich early M-dwarf

Abstract

We report the confirmation and analysis of TOI-5349b, a transiting, warm, Saturn-like planet orbiting an early M-dwarf with a period of $\sim$3.3 days, which we confirmed as part of the Searching for GEMS (Giant Exoplanets around M-dwarf Stars) survey. TOI-5349b was initially identified in photometry from NASA's Transiting Exoplanet Survey Satellite (TESS) mission and subsequently confirmed using high-precision radial velocity (RV) measurements from the Habitable-zone Planet Finder (HPF) and MAROON-X spectrographs, and from ground-based transit observations obtained using the 0.6-m telescope at Red Buttes Observatory (RBO) and the 1.0-m telescope at the Table Mountain Facility of Pomona College. From a joint fit of the RV and photometric data, we determine the planet's mass and radius to be $0.40\pm 0.02{\mathrm{M}}_{\mathrm{J}}$ ($127.4_{-5.7}^{+5.9}{M}_{\oplus }$) and $0.91\pm 0.02{\mathrm{R}}_{\mathrm{J}}$ ($10.2\pm 0.3R_{\oplus }$), respectively, resulting in a bulk density of $\ddot{I}{}_p=0.66\pm 0.06\mathrm{g}\mathrm{c}{\mathrm{m}}^{-3}$ ($\sim$0.96 the density of Saturn). We determine that the host star is a metal-rich M1-type dwarf with a mass and radius of $0.61\pm 0.02M_{\odot }$ and $0.58\pm 0.01R_{\odot }$, and an effective temperature of $T_{\mathrm{eff}}=3751\pm 59$ K. Our analysis highlights an emerging pattern, exemplified by TOI-5349, in which transiting GEMS often have Saturn-like masses and densities and orbit metal-rich stars. With the growing sample of GEMS planets, comparative studies of short-period gas giants orbiting M-dwarfs and Sun-like stars are needed to investigate how metallicity and disk conditions shape the formation and properties of these planets.

24 pages, 8 figures, 4 tables, submitted to AAS