TRAPPIST-1
(TFS) - 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.
Planetary
system
In February 2017, astronomers announced that the
planetary system of this star 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 intermediate in size between Mars and Earth. Three of the planets
(e, f and g) orbit within the habitable zone.
The system is very flat and compact. All seven of
TRAPPIST-1's planets orbit much closer than Mercury orbits the Sun. Except for
TRAPPIST-1b, they orbit farther than the Galilean satellites do around Jupiter,
but closer than most of the other moons of Jupiter. The distance between the
orbits of TRAPPIST-1b and TRAPPIST-1c is only 1.6 times the distance between
the Earth and the Moon. The planets should appear prominently in each other's
skies, in some cases appearing several times larger than the Moon appears from
Earth. A year on the closest planet passes in only 1.5 Earth days, while the
seventh planet's year passes in only 18.8 days.
