One of the outer planets of the TRAPPIST 1 system that resides in the habitable zone, where water can be maintained in a liquid state, has conditions to retain a long-term atmosphere and be fit for life, astronomers have recently found.
The TRAPPIST-1 star system is composed of seven temperate terrestrial planets, of which five (b, c, e, f, and g) are similar in size to Earth, and two (d and h) are of an intermediate size ranging in size between Mars and Earth. Three of the planets (e, f, and g) orbit within the habitable zone of the star.
A team of astronomers led by Michaël Gillon of the Institute of Astrophysics and Geophysics at the University of Liège in Belgium used the TRAPPIST telescope (Small Telescope for Planets and Planetesimals in Transit) at the La Silla Observatory in the Atacama Desert ( Chile) to observe TRAPPIST-1 and search it for potential planets.
So far, this is the most promising solar system discovered to date, that may host life as we know it.
What do we know so far?
TRAPPIST-1 is located around 40 light years from Earth and as we’ve already indicated, astronomers know that there are seven rocky planets orbiting the star, similar in size to Earth and three of those planets could contain water on their surface.
TRAPPIST-1 is a red dwarf star. It’s cooler, smaller, and much more active than our sun, despite being the size of Jupiter. Its stellar flares can erupt out to millions of miles, which isn’t really good news as its outermost planet is only 5.5 million miles away. Furthermore, each planet is located about a quarter-of-a-million-miles away from each other at closest approach.
Despite the fact that TRAPPIST-1 planets may be bombarded by solar flares, astronomers have recently found that all seven planets could retain their atmosphere, but the more likely scenario is that the outermost two planets orbiting the red dwarf, -1g and -1h, have the best odds.
Now, a new study published in PNAS has determined the atmospheric escape rates for the planets of TRAPPIST-1 and shows that it is likely that TRAPPIST-G, located within the habitable zone, may have the ability to retain its atmosphere on a timescale of billions of years. This means that TRAPPIST-1G has great odds of having water on its surface, and when looking for alien life, we consider water as the number one key ingredient.
“…the outer planets are potentially likely to retain their atmospheres over billion-year timescales.”
Further studies will be made when the James Webb Space Telescope becomes active in 2019, and astronomers will use it to detect traces of the atmospheres on the planets, proving more accurate data and perhaps even answering whether or not the planets of the TRAPPIST-1 system are habitable and suitable for life as we know it.