A red dwarf is a type of star that is smaller than our sun. They are also cooler and fainter. Because of that, a planet orbiting these stars would need to be closer to it than we are to the sun.
The new study found that planets that circle these weakling stars at a certain distance could be habitable — meaning the planet could have liquid water and potentially support life. It will be published in an upcoming issue of The Astrophysical Journal.
The researchers, are the Harvard-Smithsonian Center for Astrophysics, used data from NASA's Kepler telescope (which has been searching for planets circling other stars since 2009) to determine that about six percent of red dwarves have an Earth-sized planet in their habitable zone.