A trio of Earths 40 light years away?
But this also presents a difficulty. These stars only emit a small amount of light, most of the time they can only be detected in the infrared by the most powerful instruments. Those that are closest to the Earth have just begun to be studied and TRAPPIST-1 has itself only recently been discovered. At distances of around one hundred light years they remain unobservable while more massive stars like the sun emit a signal that is visible over distances of several thousand light years. “Therefore, there are a lot fewer known ultracool red dwarf stars than large stars due to the fact that we can only detect the closest ones. Up to now, research campaigns have concentrated on finding as many exoplanets as possible while probing large sections of the heavens without categorizing the type of stars. This made it possible to study thousands of stars at the same time therefore increasing the chances of detection, but included almost no ultracool red dwarf stars”, explains Emmanuël Jehin. Finally, up to the present time, the scientific community has depicted these stars as being too active, with an emission of light that is too variable to allow for the detection of planetary transits, the presence of which was very doubtful anyway, according to the results of several models. In a nutshell, these planets were considered to be of little interest for planetary research due to the fact that they were so different from the sun.
The researchers from Liege think the opposite and they believe that almost all of these stars hide a planetary system as this first discovery seems to confirm. Concentrating on ultracool red dwarf stars would seem to be a promising prospect. “In addition”, adds Michaël Gillon, “the large telescopes of the future such as the JWST, NASA’s next space telescope, will have a degree of precision that will enable them to study the atmosphere of Earth-like planets and even find traces of life, but only around the nearest and smallest stars. For bigger stars that are further away, we will have to wait for more powerful instruments”.