Early-M dwarfs occurrence rates

From the detectability function we can calculate the occurrence rate of small mass planets around early-M dwarfs, either taking into account only the 11 already published HADES planets or adding also the 5 new planetary candidates discovered in this analysis, and compare them with the previous estimates of planet occurrence around M-dwarf or Solar-type stars: considering only the confirmed planets, we find the highest frequency for low-mass planets (1M_{earth}<m_p_sini<10M_{earth}) with periods 10d<P< 100d, f_occ_=85^+5^_-19_%, while for short-period planets (1d<P<10d) we find a frequency of f_occ_=10.3^+8.4^_-3.3_%, significantly lower than for later-M dwarfs; if instead we take into account also the new candidates, we observe the same general behaviours, but with consistently higher frequencies of low-mass planets.

We also present new estimates of the occurrence rates of long-period giant planets and temperate planets inside the Habitable Zone of early-M dwarfs: in particular we find that the frequency of habitable planets could be as low as eta_{earth}<17.1%. These results, and their comparison with other surveys focused on different stellar types, confirms the central role that stellar mass plays in the formation and evolution of planetary systems.