The discovery of seven exo-planets around one ultracool red dwarf star, Earlier in 2016, scientists detected a planet orbiting the star Proxima Centauri (a red dwarf), our nearest stellar neighbour; So, in this post I'd discuss the habitability of planets around these type of stars.
The habitability of red dwarf systems is determined by a large number of factors from a variety of sources. Although the low stellar flux, high probability of tidal locking, small circumstellar habitable zones, and high stellar variation experienced by planets of red dwarf stars are impediments to their planetary habitability, the ubiquity and longevity of red dwarfs are positive factors. Determining how the interactions between these factors affect habitability may help to reveal the frequency of extraterrestrial life and intelligence.
Intense tidal heating caused by the proximity of planets to their host red dwarfs is a major impediment to life developing in these systems. Other tidal effects, such as the extreme temperature differences created by one side of habitable-zone planets permanently facing the star and the other perpetually turned away and lack of planetary axial tilts, reduce the probability of life around red dwarfs. Non-tidal factors, such as extreme stellar variation, spectral energy distributions shifted to the infrared relative to the Sun, and small circumstellar habitable zones due to low light output, further reduce the prospects for life in red-dwarf systems.
There are, however, several effects that increase the likelihood of life on red dwarf planets. Intense cloud formation on the star-facing side of a tidally locked planet may reduce overall thermal flux and drastically reduce equilibrium temperature differences between the two sides of the planet. In addition, the sheer number of red dwarfs, which account for about 85% of at least 100 billion stars in the Milky Way, statistically increases the probability that there might exist habitable planets orbiting some of them. As of 2013, there are expected to be tens of billions of super-Earth planets in the habitable zones of red dwarf stars in the Milky Way.