We report the discovery and validation of TOI 122b and TOI 237b, two warm planets transiting inactive M dwarfs observed by \textit{TESS}. Our analysis shows TOI 122b has a radius of 2.72±0.18 R_\rm{e} and receives 8.8±1.0× Earth's bolometric insolation, and TOI 237b has a radius of 1.44±0.12 R_\rm{e} and receives 3.7±0.5× Earth insolation, straddling the 6.7× Earth insolation that Mercury receives from the sun. This makes these two of the cooler planets yet discovered by \textit{TESS}, even on their 5.08-day 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.
@article{arxiv.2010.15905,
title = {TOI 122b and TOI 237b, two small warm planets orbiting inactive M dwarfs, found by \textit{TESS}},
author = {William C. Waalkes and Zachory K. Berta-Thompson and Karen A. Collins and Adina D. Feinstein and Benjamin M. Tofflemire and Bárbara Rojas-Ayala and Michele L. Silverstein and Elisabeth Newton and George R. Ricker and Roland Vanderspek and David W. Latham and S. Seager and Joshua N. Winn and Jon M. Jenkins and Jessie Christiansen and Robert F. Goeke and Alan M. Levine and H. P. Osborn and S. A. Rinehart and Mark E. Rose and Eric B. Ting and Joseph D. Twicken and Khalid Barkaoui and Jacob L. Bean and César Briceño and David R. Ciardi and Kevin I. Collins and Dennis Conti and Tianjun Gan and Michaël Gillon and Giovanni Isopi and Emmanuël Jehin and Eric L. N. Jensen and John F. Kielkopf and Nicholas Law and Franco Mallia and Andrew W. Mann and Benjamin T. Montet and Francisco J. Pozuelos and Howard Relles and Jessica E. Libby-Roberts and Carl Ziegler},
journal= {arXiv preprint arXiv:2010.15905},
year = {2020}
}