2026/04/29 by Pranav H. Premnath, Paul Robertson, Shubham Kanodia +33
#astro-ph.EP
paper · pdf · doi:10.3847/1538-3881/ae82d3
We report the confirmation and characterization of four transiting giant planets orbiting early-M dwarfs discovered by the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey: TOI-7189 b, TOI-7265B b, TOI-7393 b, and TOI-7394B b. Joint modeling of TESS and ground-based photometry with precision radial velocities from the Habitable-zone Planet Finder and NEID spectrographs yields self-consistent orbital and physical parameters for all systems. The planets have short orbital periods (P = 1.25-4.17 days), masses spanning from 0.5 M\rm J to 2.1 M\rm J, and radii comparable to Jupiter (0.95 R\rm J < Rp < 1.02 R\rm J). TOI-7189 b (0.50 M\rm J), TOI-7265B b (0.71 M\rm J), and TOI-7393 b (0.61 M\rm J) are Saturn-like in mass and density, whereas TOI-7394B b is a dense super-Jupiter (2.10 M\rm J, ρp ≈ 2.4 g cm-3) on a 1.25-day orbit. All hosts are early-M dwarfs with a narrow range of stellar properties, enabling a controlled comparison of giant-planet outcomes around low-mass stars. Three systems orbit super-solar metallicity stars, while TOI-7393 ([Fe/H] = -0.35 ± 0.16) is the most metal-poor GEMS host identified to date, and exhibits kinematics approaching the thin/thick-disk transition, suggestive of an older stellar population. Together, these systems reveal substantial diversity in the masses and bulk properties of short-period giant planets orbiting early-M dwarfs, demonstrating that markedly different planetary outcomes can arise around stars with otherwise similar fundamental properties.