Scientists discover 15 new planets orbiting red dwarf stars

Wednesday, 14 Mar, 2018

Scientists have been working on discovering more planets that could harbor life as we know it on Earth.

Aside from the discovery of a possible super-Earth, the research found that planets orbiting red dwarfs - small, cool and abundant stars - could have very similar characteristics to planets orbiting stars that resemble our own sun. Follow-up observations were then made on the ground with the Subaru telescope in Hawaii, and the Nordic Optical Telescope (NOT) in Spain.

Per the study, K2-155, one of the red dwarf star discovered by the Kepler K2 Mission is located at a distance of about 200 light-years away from Earth. After combining the data from the different telescopes, they discovered that K2-155d could potentially host liquid water on its surface.

"In our simulations, the atmosphere and the composition of the planet were assumed to be Earth-like, and there's no guarantee that this is the case", Teruyuki Hirano, the lead researcher of the new study, from the Tokyo Institute of Technology, said in a statement. But the two new studies still yielded substantial takeaways, including the observation that planets orbiting red dwarfs might be similar to those that orbit stars with similar characteristics to the sun, though they may be smaller in number than those that orbit "solar-type stars".

"Large planets are only discovered around metal-rich stars. Red dwarf systems, especially coolest red dwarfs, are just beginning to be investigated, so they are very exciting targets for future exoplanet research", said Hirano.

Astronomers will have to calculate K2-155d's radius and temperature to see if it really is habitable. The planets orbiting red dwarfs are usually tidally locked to the star, meaning that only one side of the planet is lightened by the star and the other side is in darkness.

Out of the 15 new exoplanets, there is a system that has three super-Earths, and the super-Earth that is orbiting at the farthest location away from its star could be in its habitable zone.

Of the three planets, the outermost one, K2-155d, sits in the star's Goldilocks Zone - the region in space around a host star which is neither too hot nor too cold, giving it decent conditions of sustainable life.

"This is a unique finding, and many theoretical astronomers are now investigating what causes this gap", Hirano added.

The studies were conducted as part of the KESPRINT collaboration, a group formed by the merger of KEST (Kepler Exoplanet Science Team) and ESPRINT (Equipo de Seguimiento de Planetas Rocosos Intepretando sus Transitos) in 2016.

"TESS is expected to find many candidate planets around bright stars closer to Earth". The results show a "radius gap", or a dip in the number of stars with a radius between 1.5-2.0 times that of Earth. Planets like Jupiter and Saturn are believed to have grown so large because their atmosphere had room to expand, and as such, it makes sense that a red dwarf might not provide the adequate environment for this process to take place.