Earlier this year, NASA made headlines when they announced the finding of seven Earth-sized planets just 40 light years away. Three of the TRAPPIST-1 planets are within the star's goldilocks zone. But now, it's looking improbable that life will be discovered within the TRAPPIST system.
Two different teams at the Harvard-Smithsonian Center for Astrophysics say the conduct of the star makes it less probable than we'd believed (or hoped) that the system could sustain life. The star in question, TRAPPIST-1, is a red dwarf that is much dimmer and cooler than the Sun. Consequently, to be in the goldilocks zone, planets must be much nearer to the star than the Earth is to our sun. The news is grim: The UV radiation the goldilocks zone planets experience is much more than Earth's.
"Because of the onslaught by the star's radiation, our results suggest the atmosphere on planets in the TRAPPIST-1 system would largely be destroyed," says Avi Loeb, coauthor of a paper published in the International Journal of Astrobiology.
The team approximates that the probability that life could exist on TRAPPIST-1's goldilocks zone planets is just 1%, as compared to the possibility for life existing on Earth.
A different study published in The Astrophysical Journal Letters inspects the solar wind of TRAPPIST-1. While Earth receives a stream of solar particles from the Sun, we're generally sheltered by our magnetic field. The TRAPPIST-1 planets also probably have magnetic fields, but the problem is their nearness to the star. Since they're so close, the magnetic field of the star could in fact be combined with the planets'. This means that the magnetic field wouldn't be the obstruction it is for the Earth; if the solar wind is sturdy enough, it could strip atmosphere from the planets. Without atmosphere, life has no chance of surviving.
It's important to recollect that "goldilocks zone" only means one thing: A planet is close enough to its star to be warm enough to sustain liquid water. It doesn't take into account the countless problems a star or planetary system might have. This doesn't mean that there conclusively is not life in TRAPPIST-1, nor that we won't find life in other red giant systems. It just means that it's less probable than we'd formerly hoped, and that we should keep searching.