Newfound 'super-Earth' exoplanets bear clues about atmospheres of alien worlds

By Charles Q. Choi 6 hours ago

An artist's impression of the star Gliese 887 and its planetary system.
(Image: © University of Göttingen)


The brightest red dwarf star in the sky may be the best chance astronomers have yet to analyze the atmospheres of alien worlds — and perhaps detect whether those worlds have life, a new study finds.

Scientists focused on the red dwarf star GJ 887, also known as Gliese 887. (Red dwarfs are the most common kind of star in the galaxy, and weigh between 7.5% and 50% the mass of the sun.) At a distance of about 10.7 light-years from Earth, Gliese 887 is the twelfth-closest star. Furthermore, at visible wavelengths, Gliese 887 is the brightest red dwarf in the sky, and with nearly half the sun's mass, Gliese 887 is the heaviest red dwarf star within about 20 light-years of Earth.

Previous work found that many red dwarfs host planetary systems, ones usually made up of multiple small worlds. Still, "we've been looking for exoplanets orbiting Gliese 887 for nearly 20 years, and while we saw hints of a planetary signal, it wasn't strong enough to convince ourselves that it was a planet," study lead author Sandra Jeffers, an astrophysicist at the University of Göttingen in Germany, told Space.com.

Pressing forward, the researchers examined Gliese 887 for 80 nights in 2018. They relied on the High Accuracy Radial Velocity Planet Searcher (HARPS) instrument at La Silla Observatory in Chile, combining this data with archival measurements of the star spanning nearly two decades.

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