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TOI-3235 b: A Transiting Giant Planet around an M4 Dwarf Star

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jats:titleAbstract</jats:title> jats:pWe present the discovery of TOI-3235 b, a short-period Jupiter orbiting an M dwarf with a stellar mass close to the critical mass at which stars transition from partially to fully convective. TOI-3235 b was first identified as a candidate from TESS photometry and confirmed with radial velocities from ESPRESSO and ground-based photometry from HATSouth, MEarth-South, TRAPPIST-South, LCOGT, and ExTrA. We find that the planet has a mass of 0.665 ± 0.025 jats:italicM</jats:italic> jats:subJ</jats:sub> and a radius of 1.017 ± 0.044 jats:italicR</jats:italic> jats:subJ</jats:sub>. It orbits close to its host star, with an orbital period of 2.5926 days but has an equilibrium temperature of ≈ 604 K, well below the expected threshold for radius inflation of hot Jupiters. The host star has a mass of 0.3939 ± 0.0030 jats:italicM</jats:italic> jats:sub☉</jats:sub>, a radius of 0.3697 ± 0.0018 jats:italicR</jats:italic> jats:sub☉</jats:sub>, an effective temperature of 3389 K, and a jats:italicJ</jats:italic>-band magnitude of 11.706 ± 0.025. Current planet formation models do not predict the existence of gas giants such as TOI-3235 b around such low-mass stars. With a high transmission spectroscopy metric, TOI-3235 b is one of the best-suited giants orbiting M dwarfs for atmospheric characterization.</jats:p>



5109 Space Sciences, 51 Physical Sciences, 5101 Astronomical Sciences

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Astrophysical Journal Letters

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American Astronomical Society