Earlier this year, the science world was abuzz with news about TRAPPIST-1, a star system with several newly-discovered Earth-like planets, which seemed like good candidates for alien life.
Not only did these planets have the right size and temperature range for life, there was also evidence showing the presence of liquid water.
Sounds pretty comfortable, right?
Not so fast. There are other factors that affect how hospitable planetary environments can be, and the most recent news about TRAPPIST-1 might significantly lower the chances of life being found there.
The new observations come from the Kepler Space Telescope. Astronomers monitoring TRAPPIST-1 over an 80-day period observed dozens of intense solar flares emanating from the star, with an average frequency of about one flare every 28 hours.
The largest of these was roughly equivalent to the Carrington Event of 1859, the largest solar flare ever recorded in our own system, which was so intense that it led to aurorae bright enough to wake people in the middle of the night, and caused power lines to surge.
If it were to happen again today, it would completely knock out our global communications system.
Keeping in mind that Carrington was our biggest-ever flare in centuries of recorded observations, it is unlikely that astronomers just happened to catch an equally rare event happening in TRAPPIST-1 during their 80-day window of observations.
The better explanation is that these sorts of intense outbursts are common there, especially given how volatile the star was throughout the observation period. That, in turn, suggests that for TRAPPIST-1, events of Carrington-like rarity could be much, much more intense.
But the Carrington Event didn’t cause a mass extinction on Earth, so why should any life on the planets of TRAPPIST-1 have trouble surviving a constant barrage of solar flares?
The trouble is that all those flares in short succession would lead to unstable atmospheres on all of TRAPPIST-1’s Earth-like planets, to the point that life probably could never have started there (or at least not the life that these planets’ specifications gave us reason to hope for).
Of course, it is possible that these planets have very strong magnetospheres, which would help their atmospheres to withstand the flares.
Earth has a magnetosphere with a strength of approximately 0.5 Gauss, which was enough to withstand the Carrington Event. But for the planets in the TRAPPIST-1 system to have stable atmospheres with this kind of constant flare activity, they probably need magnetospheres with strengths in the order of hundreds of Gauss.
The research is still undergoing peer review, but you can read the findings online.
In the meantime, this is not a good reason to stop looking for life in the wider universe.
But don’t pack your bags for TRAPPIST-1 just yet.