Researchers at the Harvard-Smithsonian Center for Astrophysics reported using publicly available data from NASA's Kepler space telescope to determine the likelihood of a red dwarf having a planet that is both habitable and Earth-sized.
"We thought we would have to search vast distances to find an Earth-like planet," Harvard astronomer Courtney Dressing said. "Now we realize another Earth is probably in our own back yard, waiting to be spotted."
Red dwarf stars are smaller, cooler, and on average only one-third as large and one-thousandth as bright as the sun.
While none are visible to the naked eye from Earth they are good candidates for a search for Earth-like planets, astronomers said, since they make up three out of every four stars in our galaxy for a total of at least 75 billion.
Statistically, a red dwarf hosting an Earth-like habitable planet could be as close as 13 light years to Earth, they said.
"We now know the rate of occurrence of habitable planets around the most common stars in our galaxy," study co-author David Charbonneau said. "That rate implies that it will be significantly easier to search for life beyond the solar system than we previously thought."