CAPE CANAVERAL, Fla. — Astronomers searching for life beyond our solar system might need to look no farther than a little, feeble nearby star.
A Belgian-led team reported Monday that it has discovered three Earth-size planets orbiting an ultra-cool dwarf star less than 40 light-years away. It’s the first time planets have been found around this type of star — and it opens up rich territory in the search for extraterrestrial life.
Because this star is so close and so faint, astronomers can study the atmospheres of these three temperate exoplanets and, eventually, hunt for signs of possible life. They’re already making atmospheric observations, in fact, using NASA’s Spitzer Space Telescope. The Hubble Space Telescope will join in next week.
Altogether, it’s a “winning combination” for seeking chemical traces of life outside our solar system, said Massachusetts Institute of Technology researcher Julien de Wit, a co-author of the study, released by the journal Nature.
The star in question — named Trappist-1 after the Belgian telescope in Chile that made the discovery — is barely the size of Jupiter and is in the constellation Aquarius.
Other exoplanet searches have targeted bigger, brighter stars more like our sun, but the starlight in these cases can be so bright that it washes out the signatures of planets. By comparison, cool dwarf stars that emit infrared light, like Trappist-1, make it easier to spot potential worlds.
University of Liege astronomers in Belgium — lead study authors Michael Gillon and Emmanuel Jehin — built the Trappist telescope to observe 60 of the nearest ultra-cool dwarf stars. The risky effort paid off, de Wit said in an e-mail.
The two inner exoplanets take from 1.5 to 2.4 days to orbit the Trappist-1 star. The precise orbit time of the third planet is not known. Spitzer and Hubble should answer whether the exoplanets have large and clear atmospheres, according to de Wit. They also might be able to detect water and methane, if molecules are present.
