TOI 122b and TOI 237b, two small warm planets orbiting inactive M dwarfs, found by \textit{TESS}

TL;DR

This paper reports the discovery of two small, warm planets orbiting inactive M dwarfs by TESS, which are valuable for studying planetary atmospheres and volatile evolution around low-mass stars.

Contribution

First validation of two small warm planets around inactive M dwarfs by TESS, expanding the known population near the small-planet radius valley.

Findings

TOI 122b has a radius of 2.72 R⊕ and receives 8.8 times Earth's insolation.

TOI 237b has a radius of 1.44 R⊕ and receives 3.7 times Earth's insolation.

Both planets are potential targets for future atmospheric studies.

Abstract

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$\pm$0.18 R$_\rm{e}$ and receives 8.8$\pm$1.0$\times$ Earth's bolometric insolation, and TOI 237b has a radius of 1.44$\pm$0.12 R$_\rm{e}$ and receives 3.7$\pm$0.5$\times$ Earth insolation, straddling the 6.7$\times$ 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$\pm$0.21 pc and 38.11$\pm$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.