Abstract EANA2026-67

The Habitable Zone (HZ) is defined by the possibility of sustaining liquid water on a planetary surface. We show that planets orbiting M- and K-stars may maintain liquid water on their night side, significantly closer to their host star than the inner border of the conservative HZ. We show that the extension of the habitable zone (HZ) due to the presence of liquid water on the nightside of tidally locked planets significantly increases the number of potentially habitable planets. Calculating the occurrence of habitable planets orbiting M-, K-, and G-dwarf stars within the conservative and extended HZ, we show that potentially habitable planets may be as much as 50 times more abundant than in the conservative HZ of G-type stars only. We find that the extended HZ could imply more than one habitable planet per star, and hundreds of habitable planets within 10 pc from Earth. This dramatically enhances the number of potential candidates for biosignature follow-up observations by JWST and Roman.

 

Exoplanets beyond the Conservative Habitable Zone. I. Habitability, Wandel, A. 2026, Astrophys. J. 996, 132.

Exoplanets beyond the Conservative Habitable Zone. II. Occurrence. Wandel, A. 2026, Astrophys. J. 996, 133.