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Astrometry and celestial mechanics

A slew of telescopes on three continents have set their sights on Barnard’s Star, allowing researchers to accumulate some 800 observations over the course of 20 years. The study authors also drew on data collected by amateur astronomers.

It took the combined efforts of more than 50 researchers at some two dozen institutions, but “slowly a signal in our data came out of all the noise,” said astronomer Ignasi Ribas, who is director of the Institute of Space Studies in Catalonia, Spain, and the lead author of the Nature paper.

An artist’s impression of the view from the surface of a planet orbiting Barnard’s Star. (M. Kornmesser/European Southern Observatory)

Barnard’s Star’s periodic wobble suggests it is circled by a large planet once every 233 days. Very few exoplanets have been found so far from their stars (planets with short orbital periods generate more frequent signals, making them easier to detect).

Because Barnard’s Star is so dim, the planet’s long orbital period puts it at the “snow line,” where sunlight is so faint that its surface is perpetually frozen. Its average surface temperature is possibly a brisk -150 degrees Celsius (-238 degrees Fahrenheit).