Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf

Varghese Reji; Shubham Kanodia; Joe Ninan; Caleb I. Cañas; Jessica Libby-Roberts; Andrea S. J. Lin; Arvind F Gupta; Tera N. Sewaby; Alexander Larsen; Henry A. Kobulnicky; Philip I. Choi; Nez Evans; Sage Santomenna; Isabelle Winnick; Larry Yu; Jaime A. Alvarado-Montes; Chad Bender; Lia Marta Bernabò; Cullen H. Blake; William D. Cochran; Scott A. Diddams; Samuel Halverson; Te Han; Fred Hearty; Sarah E. Logsdon; Suvrath Mahadevan; Andrew Monson; Michael McElwain; Paul Robertson; Devendra Ojha; Arpita Roy; Christian Schwab; Gudmundur Stefansson; Jason Wright

arXiv · 2409.01371

Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf

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Abstract

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.

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Varghese Reji, Shubham Kanodia, Joe Ninan, Caleb I. Cañas, Jessica Libby-Roberts, Andrea S. J. Lin, Arvind F Gupta, Tera N. Sewaby, Alexander Larsen, Henry A. Kobulnicky, Philip I. Choi, Nez Evans, Sage Santomenna, Isabelle Winnick, Larry Yu, Jaime A. Alvarado-Montes, Chad Bender, Lia Marta Bernabò, Cullen H. Blake, William D. Cochran, Scott A. Diddams, Samuel Halverson, Te Han, Fred Hearty, Sarah E. Logsdon, Suvrath Mahadevan, Andrew Monson, Michael McElwain, Paul Robertson, Devendra Ojha, Arpita Roy, Christian Schwab, Gudmundur Stefansson, Jason Wright. 2024-09-02. Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf. https://arxiv.org/abs/2409.01371

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