On the Habitability of Teegarden's Star Planets

We study the habitability of the two 1.3+0.3 0.7 Earth-mass planets, recently detected by the CARMENES collaboration, around the ultra-cool nearby M-dwarf Teegarden's Star. With orbital periods of 4.9 and 11.4 days, both planets are likely to be within the habitable zone and tidally locked. They are among the most Earth-like exoplanets yet discovered. Applying an analytic habitability model we find that surface liquid water could be present on both planets for a wide range of atmospheric properties, which makes them attractive targets for biosignature searches. The prospects of the planets retaining such an atmosphere over their history are discussed.