Stellar flares may hamper search for life in promising star system

The search for atmospheres around the Trappist-1 star system, one of the most promising places in life elsewhere in the galaxy, could be even more difficult than astronomers thought because of the short-term radiation explosions of the star.

Trappist-1, discovered for the first time in 2016, is a small red dwarf star about 40 light years from the earth with at least seven orbit planets. It is a privileged target for astronomers hoping to detect extraterrestrial life because several of its planets seem to be in a habitable area where temperatures are right for liquid water.

But to support life, these planets should keep atmospheres. Until now, in -depth observations with the James Webb space telescope have not found any evidence of atmospheres on any of the planets.

Now Julien de Wit at the Massachusetts Institute of Technology and his colleagues have detected microflares from the Star Trappist-1 every hour that last several minutes. These tiny radiation gusts seem to interfere with our ability to observe the light that goes through the atmospheres of the planets – if they exist – thwart the main method of detection of chemicals in all atmospheres.

Using the Hubble space telescope, from Wit and his team sought a specific wavelength of ultraviolet light from Trappist-1 which is absorbed by hydrogen. If they saw less of this light than expected when a planet has passed in front of the star, it might suggest that hydrogen escapes from the atmosphere of the planet.

They found no sign of this, but they found a significant variability between different observations, which suggests that additional light came from somewhere at certain times. Since the Hubble data can be divided into 5 -minute pieces, they could see that the additional light was very short. De Wit and his team say that the source must be microflares – gusts of radiation from the star, such as solar eruptions on our sun but more frequent.

The Trappist-1 star is extremely low, which means that astronomers must observe it for a long time to collect enough light. “In addition to that, there is this flared activity, on a time -relevant time scale for the time ladders in transit planets,” explains Wit. “It seems that it is really very difficult to say something really informative about the presence of [atmospheres on the exoplanets]Said Wit.

He and his colleagues also calculated whether these lighting rockets could affect the capacity of the planets to keep atmospheres. A planet, Trappist-1b, on which the James Webb space telescope had not already found evidence of atmosphere, could lose the equivalent of 1000 times all hydrogen in the oceans of the earth every million years, they found. However, there are still a lot of unknowns and a wide range of different scenarios, says of Wit, in part because we do not know how many of these fusted rockets really hit the planets.

Stars like this can have a range of activity levels, but it seems that Trappist-1 can be towards the most active side of this range, explains Ekaterina Ilin in the Netherlands Institute for Radio Astronomy. “It is not as if it was an absolutely unexpected result and another world; It’s just a kind of bad luck. It is more active than we hoped, ”she says. “In a way, it’s really new to see these enlightening rockets, or what we interpret at least like this, if they are what they think. It could be one of the first cases of such a small star. ”