BY JAMES MAYNARD
The TRAPPIST-1 solar system could contain two planets capable of supporting alien life, according to a new study. Astronomers currently know of seven planets in the system, the greatest collection of planets known outside our own stellar family. Of these, three orbit their sun in the habitable zone, at distances where water could exist in liquid form, increasing the chances of life.
The two worlds in the TRAPPIST-1 system currently attracting attention are believed to have warm temperatures, and liquid water on their surfaces. Researchers theorize that the fourth and fifth known planets in that system, designated d and e, are the most likely to harbor life.
“With the exception of TRAPPIST-1c, all seven of the planets have densities low enough to indicate the presence of significant H2O in some form. Planets b and c experience enough heating from planetary tides to maintain magma oceans in their rock mantles; planet c may have eruptions of silicate magma on its surface, which may be detectable with next-generation instrumentation,” Amy Barr of the Planetary Science Institute and other researchers stated in an article detailing their study of the alien worlds.
Astronomers modeled orbits of the exoplanets to determine surface temperatures on the alien worlds. TRAPPIST-1e is the colder of the two potentially habitable worlds, with temperatures approximately as cool as Antarctica. Although cold, these conditions could certainly be home to living beings. One planet closer to its sun, temperatures on TRAPPIST-1d likely average around 15C (59F).
Water and heat sources were also examined by the investigators, in an effort to determine which of the worlds in that alien system were most suitable for life.
“The planets are also on eccentric orbits – kind of egg-shaped – so every time the planet goes around the star it gets stretched and squeezed,” Barr explained to The Guardian.
This tidal heating also takes place in the Earth-Moon system here at home, although the amount of heating provided to Earth from the gravitation of the Moon is relatively small. However, this effect is more pronounced within our planetary companion. Such an effect on an alien world could not only warm that planet, but also drive chemical reactions, leading to an increased chance of developing life.
The seven planets in the TRAPPIST-1 system were discovered in 2017.
Image: An artist’s conception of the seven known worlds in the TRAPPIST-1 system. Credit: JPL / NASA/JPL-Caltech