Abstract:
The number of discovered exoplanets reached thousands, allowing us to look not only at individual planets’ occurrence trends but also improve our chances of finding a habitable Earth analogue. The occurrence of such terrestrial planets points on host stars different from the Sun towards dimmer stars such as M dwarfs. Not only it is easier to detect small planets around M dwarfs, but they also comprise 75% of stars in the solar neighbourhood. The disadvantage of studying cool stars as habitable planet hosts is their enhanced activity, namely frequent flares. Flares are very complicated both spectrally and temporally. They are stochastic, fast events, posing observational challenges for UV observation from the ground and even from space (for extreme UV). The models of stellar atmospheres coupled with radiative-transfer calculation can help to overcome the lack of observations. Modelled variability of the M dwarf spectre can be input for modelling photo-chemical processes in the exoplanet atmosphere. These models can predict the ultimate fate of the primordial atmosphere and increase or eliminate the chances for the planet to sustain life. Studying M dwarfs remains our best chance to achieve the detection of the first habitable planet other than Earth.