A potentially habitable exoplanet is a hypothetical type of planet that has liquid water and may support life. As of March 2020, a total of 55 potentially habitable exoplanets have been found. Of those, one is believed to be Sub-terran (Mars-size), 20 Terran (Earth-size) and 34 Super Terran (Super Earths). The main feature of potentially habitable exoplanets is that they have to be located in the habitable zone of their stellar systems.
In order to be potentially habitable, an exoplanet would have to have a mass between 0.1 and 10 Earth masses.
The radius of a habitable exoplanet would range between 0.5 and 2.5 Earth radii.
It is believed that F, G, K and M-type star could host habitable exoplanets. G-type stars would allow to host the exoplanets most similar to Earth, that is, Earth-like planets. K-type stars would provide the necessary conditions for super habitable exoplanets, which are exoplanets that could be more habitable than Earth. As of March 2020, only one potentially habitable exoplanet has been found orbiting a F-type star: Kepler-1632 b.
M-type stars also considered possible hosts of habitable exoplanets, even those with flares such as Proxima b. However, it is important to bear in mind that flare stars could greatly reduce the habitability of exoplanets by eroding their atmosphere.
About half of the stars similar in temperature to our Sun could have a rocky planet able to support liquid water on its surface, according to research using data from NASA’s Kepler Space Telescope.