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arXiv · 2304.04730

TOI-3785 b: A Low-Density Neptune Orbiting an M2-Dwarf Star

Luke C. Powers·Jessica Libby-Roberts·Andrea S. J. Lin·Caleb I. Cañas·Shubham Kanodia·Suvrath Mahadevan·Joe P. Ninan·Guðmundur Stefánsson·Arvind F. Gupta·Sinclaire Jones·Henry A. Kobulnicky·Andrew Monson·Brock A. Parker·Tera N. Swaby·Chad F. Bender·William D. Cochran·Leslie Hebb·Andrew J. Metcalf·Paul Robertson·Christian Schwab·John Wisniewski·Jason T. Wright
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Abstract

Using both ground-based transit photometry and high-precision radial velocity (RV) spectroscopy, we confirm the planetary nature of TOI-3785 b. This transiting Neptune orbits an M2-Dwarf star with a period of ~4.67 days, a planetary radius of 5.14 +/- 0.16 Earth Radii, a mass of 14.95 +4.10, -3.92 Earth Masses, and a density of 0.61 +0.18, -0.17 g/cm^3. TOI-3785 b belongs to a rare population of Neptunes (4 Earth Radii < Rp < 7 Earth Radii) orbiting cooler, smaller M-dwarf host stars, of which only ~10 have been confirmed. By increasing the number of confirmed planets, TOI-3785 b offers an opportunity to compare similar planets across varying planetary and stellar parameter spaces. Moreover, with a high transmission spectroscopy metric (TSM) of ~150 combined with a relatively cool equilibrium temperature of 582 +/- 16 K and an inactive host star, TOI-3785 b is one of the more promising low-density M-dwarf Neptune targets for atmospheric follow-up. Future investigation into atmospheric mass loss rates of TOI-3785 b may yield new insights into the atmospheric evolution of these low-mass gas planets around M-dwarfs.

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Luke C. Powers, Jessica Libby-Roberts, Andrea S. J. Lin, Caleb I. Cañas, Shubham Kanodia, Suvrath Mahadevan, Joe P. Ninan, Guðmundur Stefánsson, Arvind F. Gupta, Sinclaire Jones, Henry A. Kobulnicky, Andrew Monson, Brock A. Parker, Tera N. Swaby, Chad F. Bender, William D. Cochran, Leslie Hebb, Andrew J. Metcalf, Paul Robertson, Christian Schwab, John Wisniewski, Jason T. Wright. 2023-04-10. TOI-3785 b: A Low-Density Neptune Orbiting an M2-Dwarf Star. https://doi.org/10.3847/1538-3881%2Facd8bf

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