Two habitable super-Earths found with agreeable temperature and conditions to keep water in liquid state
Astronomers have found two potentially habitable super-Earths, not too far away from our Sun, according to a study.
The two super-Earths - named GJ180d and GJ229Ac - are about 19 and 40 light-years away from the Earth. These planets are dubbed super-Earths because they are at least 7.5 and 7.9 times more massive than our Earth.
"Our discovery adds to the list of planets that can potentially be directly imaged by the next generation of telescopes. Ultimately, we are working toward the goal of being able to determine if planets orbiting nearby stars host life," says Carnegie’s Fabo Feng, the lead author from Carnegie Institution for Science.
These planets orbit around a class of stars home to rocky planets like our Earth: red dwarfs. Cooler and smaller than our Sun, the red dwarfs are the most common stars in the galaxy.
To detect these alien planets, the team deployed an indirect method that allows astronomers to spy on moving stars, in this case, moving red dwarfs. If a planet exists around a red dwarf, for instance, astronomers should be able to see the star moving towards and away from Earth. This is because stars are not completely at rest when they are orbited by planets because they move or wobble in response to a planet's gravitational pull.
Astronomers have the best shot at finding rocky planets around red dwarfs, thanks to their low-mass. But there is a catch: Many planets that orbit red dwarfs are tidally locked, similar to how our Moon is tidally locked to Earth. Alien planets, that are tidally locked to their stars, are not conducive to life: they have a very cold permanent night on one side and very hot permanent day on the other, says Feng.
These two super-Earths, on the other hand, are different. “GJ180d is the nearest temperate super-Earth to us that is not tidally locked to its star, which probably boosts its likelihood of being able to host and sustain life,” adds Feng.
The other super-Earth, GJ229Ac, also has an agreeable temperature and its host star has a companion in a brown dwarf - also known as failed stars.
Both these planets show potential to host life because they have an agreeable temperature, which means they have the right conditions to keep water in a liquid state.
These early findings will feed into future research, says the team.
"We eventually want to build a map of all of the planets orbiting the nearest stars to our own Solar System, especially those that are potentially habitable,” says co-author Jeff Crane, and astronomer at the Carnegie Institution for Science.
The study has been published in The Astrophysical Journal Supplement Series.