Scientists have re-estimated the age of one of the most intriguing planetary systems discovered to date, the TRAPPIST-1 system, which includes seven Earth-sized planets orbiting an ultracold dwarf star about 40 light-years away. The researchers report in new work that the TRAPPIST-1 star is quite old - its age ranges from 5.4 to 9.8 billion years. This is almost double the age of our solar system, which is estimated at about 4.5 billion years.
This age estimate for the TRAPPIST-1 system was carried out by a NASA team led by Adam Burgasser of the University of California at San Diego, USA, and is based on an analysis of the speed of the star's orbital motion around the center of the Milky Way (older stars move faster). the chemical composition of the star's atmosphere and the frequency of flares on its surface.
The "seven wonders" (seven planets) of the TRAPPIST-1 system were discovered earlier this year using the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) located in Chile, NASA's Spitzer space telescope ("Spitzer"), as well as other ground-based observatories. Three of the planets of the TRAPPIST-1 system are located in the habitable zone of the star, that is, at such a distance from the star at which a rocky planet can have water in liquid form on the surface. All seven planets are tidal in relation to the star, that is, day and night on different sides of each planet last "forever."
In general, the chances of a planet being habitable are not uniquely determined by the age of the star: on the one hand, young stars burst into frequent powerful flares that can destroy all life on the planet, and on the other hand, “mature” stars can “blow off” atmospheres over many millions of years from the surfaces of planets in their planetary systems, as happened with Mars in the solar system. Further studies will help to understand in more detail the influence of the age of the TRAPPIST-1 star on the potential habitability of the planets of its system, the authors note.
The study will be published soon in the Astrophysical Journal.