An astrophysics researcher has identified the possible compositions of the seven planets in the TRAPPIST-1 system. Using thousands of numerical simulations to identify the planets stable for millions of years, Quarles concluded that six of the seven planets are consistent with an Earth-like composition.
The exception is TRAPPIST-1f, which has a mass of 25 percent water, suggesting that TRAPPIST-1e may be the best candidate for future habitability studies.
TRAPPIST-1, also designated as 2MASS J23062928-0502285, is an ultra-cool dwarf star that is slightly larger but much more massive than the planet Jupiter, located 39.5 light-years (12.1 pc) from the Sun in the constellation Aquarius.
Seven temperate terrestrial planets have been detected orbiting the star, a larger number than detected in any other planetary system.
A study released in May 2017 suggests that the tightly packed exoplanets avoid colliding with one another due to orbits that are harmoniously resonant and, as a result, are stable for very long times.
Astronomers first discovered three Earth-sized planets orbiting the dwarf star in 2015. A team led by Michaël Gillon (fr) at the University of Liège in Belgium detected the planets using transit photometry with the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) at the La Silla Observatory in Chile.
On 22 February 2017, astronomers announced four additional exoplanets around TRAPPIST-1. This work used the NASA Spitzer Space Telescope and the Very Large Telescope at Paranal, among others, and brought the total number of planets to seven, of which three are considered to be within its habitable zone.
The others could also be habitable as they may possess liquid water somewhere on their surface.
