An artistic rendering shows what the ultracool dwarf star might look like from the surface of one of the three newly identified habitable exoplanets. Photo by ESO/M. Kornmesser
LIEGE, Belgium, May 2 (UPI) -- Astronomers at the University of Liege in Belgium have identified three new potentially habitable alien worlds surrounding a dwarf star with extremely cool temperatures.
The dwarf star TRAPPIST-1 -- named for the Belgian telescope used to discover it -- is smaller, cooler and redder than the sun. It's not much larger than Jupiter, and lies 40 light-years from the solar system within the constellation Aquarius.
While studying it, astronomers noticed periodic dimming, suggesting the ultracool star is orbited by several satellites. Closer examination revealed three identifiable exoplanets, two of which follow intimate orbits.
Researchers announced their discovery in the journal Nature.
Because the star puts off less radiation than the sun, the system's habitable zone lies much closer to the host star.
The two exoplanets that hug close to TRAPPIST-1 receive two and four times as much radiation as Earth. On average, that's too much to be considered habitable, but researchers say portions of the planet may be suitable for life.
Researchers are still trying to work out the orbit of the third exoplanet, but it likely receives less radiation than Earth -- yet still enough to create a livable planet.
Not only is TRAPPIST-1 similar in size to Jupiter, its satellites also organize themselves in a manner similar to Jupiter's moons.
"With such short orbital periods, the planets are between 20 and 100 times closer to their star than the Earth to the Sun," astronomer Michael Gillon explained in a news release. "The structure of this planetary system is much more similar in scale to the system of Jupiter's moons than to that of the Solar System."
Scientists hope to find evidence of life by analyzing the atmospheres of the three exoplanets. Most exoplanets circle stars that overwhelm attempts to study alien atmospheres, but the dimness of faint red ultra-cool dwarf stars like TRAPPIST-1 make such analysis possible.
"Thanks to several giant telescopes currently under construction, including ESO's E-ELT and the NASA/ESA/CSA James Webb Space Telescope due to launch for 2018, we will soon be able to study the atmospheric composition of these planets and to explore them first for water, then for traces of biological activity," added MIT scientist Julien de Wit. "That's a giant step in the search for life in the universe."