Searching for GEMS: TOI-5688 A b, a Low-density Giant Orbiting a High-metallicity Early M-dwarf

• DOI: 10.48550/arxiv.2409.01371
• Publication Date: 2024-01-01
• Authors: Varghese Reji; Shubham Kanodia; Joe P. Ninan; Caleb I. Cañas; Jessica Libby-Rob...; Andrea S. J. Lin; Arvind F. Gupta; Tera N. Swaby; Alexander Larsen; Henry A. Kobulnicky; Philip I. Choi; Nez Evans; Sage Santomenna; Isabelle Winnick; Larry Yu; Jaime A. Alvarado...; Chad F. Bender; Lia Marta Bernabó; Cullen H. Blake; William D. Cochran; Scott A. Diddams; Samuel Halverson; Te Han; Fred Hearty; Sarah E. Logsdon; Suvrath Mahadevan; Michael W. McElwain; Andrew Monson; Paul Robertson; Devendra K. Ojha; Arpita Roy; Christian Schwab; Gudmundur Stefansson; Jason Wright
• Keywords: Earth and Planetary Astrophysics (astro-ph.EP); Radial velocity; Astronomy; Extrasolar gaseous giant planets; FOS: Physical sciences; QB1-991; M dwarf stars; Transits; Astrophysics - Earth and Planetary Astrophysics

20 pages, 7 figures, Accepted in AJ<br/>We present the discovery of a low-density planet orbiting the high-metallicity early M-dwarf TOI-5688 A b. This planet was characterized as part of the search for transiting giant planets ($R \gtrsim8$ M${}_\oplus$) through the Searching for GEMS (Giant Exoplanets around M-dwarf Stars) survey. The planet was discovered with the Transiting Exoplanet Survey Satellite (TESS), and characterized with ground-based transits from Red Buttes Observatory (RBO), the Table Mountain Observatory of Pomona College, and radial velocity (RV) measurements with the Habitable-Zone Planet Finder (HPF) on the 10 m Hobby Eberly Telescope (HET) and NEID on the WIYN 3.5 m telescope. From the joint fit of transit and RV data, we measure a planetary mass and radius of $124\pm24$ M$_\oplus$ ($0.39\pm0.07$ M${}_J$) and $10.4\pm0.7$ R$_\oplus$ ($0.92\pm0.06$ R${}_J$) respectively. The spectroscopic and photometric analysis of the host star TOI-5688 A shows that it is a metal-rich ([Fe/H] $ = 0.47\pm0.16$ dex) M2V star, favoring the core-accretion formation pathway as the likely formation scenario for this planet. Additionally, Gaia astrometry suggests the presence of a wide-separation binary companion, TOI-5688 B, which has a projected separation of $\sim5"$ (1110 AU) and is an M4V, making TOI-5688 A b part of the growing number of GEMS in wide-separation binary systems.<br/>