A team of researchers led by Teruyuki Hirano, from the department of earth and planetary sciences in the Tokyo Institute of Technology, recently validated the discovery of 15 new exoplanets orbiting around red dwarves.
The results, published in two articles in The Astronomical Journal, were based on new data gathered by Kepler’s second mission, K2. The follow-up observations were made from earth using the Subaru telescope in Hawaii, and the Nordic Optical Telescope (PAS) in Spain. Among the stars, one of the brightest – K2-155 -is found around 200 light years from the Earth. There are three super-Earths orbiting this red dwarf, which are slightly bigger than our own planet. Of these three super-Earths, the most distant planet -K2-155d -has a radius 1.6 times that of the Earth’s, and could be within the habitable zone of its host star.
Based on tridimensional climatic simulations, the researchers explain that K2-155d could potentially have liquid water on its surface. “In our simulations, the planet’s atmosphere and composition are presumed to be similar to the Earth, but there is no guarantee that this is the case”, say the scientists. So we will have to make do with their assumptions. A more precise estimation of the radius and temperature of the star K2-155 will be necessary before concluding definitively whether K2-155d is habitable or not.
Red dwarves have often been abandoned by people seeking extraterrestrial life, who believe that their orbiting planets do not contain favourable enough conditions to support life. However, these stars, among the oldest and darkest, are extremely numerous. They are far more numerous than stars the size of our sun -and almost 75% of the stars in our galaxy. This is why astronomers are looking at them with increased interest.
They may soon employ the TESS satellite, which is due to be launched in April this year. We hope that even more planets will come to be discovered. “TESS should find numerous potential candidates in bright stars closer to the Earth”, notes Teruyuki Hirano. “It will greatly facilitate follow-up observations, including the study of planetary atmospheres, and the precise determination of the orbit of the planets.”