TOI 122b and TOI 237b: Two Small Warm Planets Orbiting Inactive M Dwarfs Found by TESS

William C. Waalkes, Zachory K. Berta-Thompson, Karen A. Collins, Adina D. Feinstein, Benjamin M. Tofflemire, Bárbara Rojas-Ayala, Michele L. Silverstein, Elisabeth Newton, George R. Ricker, Roland Vanderspek, David W. Latham, S. Seager, Joshua N. Winn, Jon M. Jenkins, Jessie Christiansen, Robert F. Goeke, Alan M. Levine, H. P. Osborn, S. A. Rinehart, Mark E. RoseEric B. Ting, Joseph D. Twicken, Khalid Barkaoui, Jacob L. Bean, César Briceo, David R. Ciardi, Kevin I. Collins, Dennis Conti, Tianjun Gan, Michaël Gillon, Giovanni Isopi, Emmanuël Jehin, Eric L.N. Jensen, John F. Kielkopf, Nicholas Law, Franco Mallia, Andrew W. Mann, Benjamin T. Montet, Francisco J. Pozuelos, Howard Relles, Jessica E. Libby-Roberts, Carl Ziegler

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


We report the discovery and validation of TOI 122b and TOI 237b, two warm planets transiting inactive M dwarfs observed by the Transiting Exoplanet Survey Satellite (TESS). Our analysis shows that TOI 122b has a radius of 2.72 ± 0.18 R ⊕ and receives 8.8 ± 1.0 times Earth's bolometric insolation, and TOI 237b has a radius of 1.44±0.12 R ⊕ and receives 3.7 ± 0.5 times Earth's insolation, straddling the 6.7 Earth insolation that Mercury receives from the Sun. This makes these two of the cooler planets yet discovered by TESS, even on their 5.08 and 5.43 day orbits. Together, they span the small-planet radius valley, providing useful laboratories for exploring volatile evolution around M dwarfs. Their relatively nearby distances (62.23 ± 0.21 pc and 38.11 ± 0.23 pc, respectively) make them potentially feasible targets for future radial velocity follow-up and atmospheric characterization, although such observations may require substantial investments of time on large telescopes.

Original languageEnglish (US)
Article number13
JournalAstronomical Journal
Issue number1
StatePublished - Jan 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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