TOI-3235 b: a transiting giant planet around an M4 dwarf star

Melissa J. Hobson*, Andrés Jordán, E. M. Bryant, R. Brahm, D. Bayliss, J. D. Hartman, G. Á. Bakos, Th. Henning, Jose Manuel Almenara, Khalid Barkaoui, Zouhair Benkhaldoun, Xavier Bonfils, François Bouchy, David Charbonneau, Marion Cointepas, Karen A. Collins, Jason D. Eastman, Mourad Ghachoui, Michaël Gillon, Robert F. GoekeKeith Horne, Jonathan M. Irwin, Emmanuel Jehin, Jon M. Jenkins, David W. Latham, Dan Moldovan, Felipe Murgas, Francisco J. Pozuelos, George R. Ricker, Richard P. Schwarz, S. Seager, Gregor Srdoc, Stephanie Striegel, Mathilde Timmermans, Andrew Vanderburg, Roland Vanderspek, Joshua N. Winn

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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 MJ and a radius of 1.017 ± 0.044 RJ. 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 M, a radius of 0.3697 ± 0.0018 R, 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.
Original languageEnglish
Article numberL4
Number of pages10
JournalAstrophysical Journal Letters
Issue number1
Early online date21 Mar 2023
Publication statusPublished - 21 Mar 2023


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