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Hartman, J. D., Bakos, G. A., Csubry, Z., Howard, A. W., Isaacson, H., Giacalone, S., et al. (2023). TOI 4201 b and TOI 5344 b: Discovery of Two Transiting Giant Planets around M-dwarf Stars and Revised Parameters for Three Others. Astron. J., 166(4), 163.
Abstract: We present the discovery from the TESS mission of two giant planets transiting M-dwarf stars: TOI 4201 b and TOI 5344 b. We also provide precise radial velocity measurements and updated system parameters for three other M dwarfs with transiting giant planets: TOI 519, TOI 3629, and TOI 3714. We measure planetary masses of 0.525 +/- 0.064 MJ, 0.243 +/- 0.020 M-J, 0.689 +/- 0.030 M-J, 2.57 +/- 0.15 M-J, and 0.412 +/- 0.040 M-J for TOI 519 b, TOI 3629 b, TOI 3714 b, TOI 4201 b, and TOI 5344 b, respectively. The corresponding stellar masses are 0.372 +/- 0.018 M-circle dot, 0.635 +/- 0.032 M-circle dot, 0.522 +/- 0.028 M-circle dot, 0.626 +/- 0.033 M-circle dot, and 0.612 +/- 0.034 M-circle dot. All five hosts have supersolar metallicities, providing further support for recent findings that, like for solar-type stars, close-in giant planets are preferentially found around metal-rich M-dwarf host stars. Finally, we describe a procedure for accounting for systematic errors in stellar evolution models when those models are included directly in fitting a transiting planet system.
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Hobson, M. J., Jordan, A., Bryant, E. M., Brahm, R., Bayliss, D., Hartman, J. D., et al. (2023). TOI-3235 b: A Transiting Giant Planet around an M4 Dwarf Star. Astrophys. J. Lett., 946(1), L4.
Abstract: We 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 M-J and a radius of 1.017 +/- 0.044 R-J. It orbits close to its host star, with an orbital period of 2.5926 days but has an equilibrium temperature of approximate to 604 K, well below the expected threshold for radius inflation of hot Jupiters. The host star has a mass of 0.3939 +/- 0.0030 M-circle dot, a radius of 0.3697 +/- 0.0018 R-circle dot;, an effective temperature of 3389 K, and a J-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.
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