| Abstract |
We present the discovery of TOI-5205~b, a transiting Jovian planet orbiting a solar metallicity M4V star, which was discovered using Transiting Exoplanet Survey Satellite photometry and then confirmed using a combination of precise radial velocities, ground-based photometry, spectra, and speckle imaging. TOI-5205~b has one of the highest mass ratios for M dwarf planets with a mass ratio of almost 0.3$\%$, as it orbits a host star that is just $0.392 \pm 0.015$ \solmass{}. Its planetary radius is $1.03 \pm 0.03~R_J$, while the mass is $1.08 \pm 0.06~M_J$. Additionally, the large size of the planet orbiting a small star results in a transit depth of $\sim 7\%$, making it one of the deepest transits of a confirmed exoplanet orbiting a main-sequence star. The large transit depth makes TOI-5205~b a compelling target to probe its atmospheric properties, as a means of tracing the potential formation pathways. While there have been radial-velocity-only discoveries of giant planets around mid-M dwarfs, this is the first transiting Jupiter with a mass measurement discovered around such a low-mass host star. The high mass of TOI-5205~b stretches conventional theories of planet formation and disk scaling relations that cannot easily recreate the conditions required to form such planets. |
| Authors |
Shubham Kanodia  , Suvrath Mahadevan , Jessica E. Libby-Roberts , Guðmundur Stefánsson , Caleb I. Cañas , Anjali A. A. Piette , Alan P. Boss , Johanna Teske , John E. Chambers , Greg Zeimann , Andrew Monson , Paul Robertson , Joe P. Ninan , Andrea S. J. Lin , Chad F. Bender , William D. Cochran , Scott A. Diddams , Arvind F. Gupta , Samuel Halverson , Suzanne L. Hawley , Henry A. Kobulnicky  , Andrew J. Metcalf , Brock A. Parker , Luke Powers , Lawrence W. Ramsey , Arpita Roy , Christian Schwab , Tera N. Swaby , Ryan C. Terrien , John P. Wisniewski
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