Earth’s new neighbor

Barnard’s Star is the closest single star to the Sun and has the fastest apparent motion across the sky. Since the 1960s all the controversial claims that have been made about the existence of exoplanets around the approximately 10-billion-year-old red dwarf have been debunked or found to be inconclusive (see the article by John Johnson, Physics Today, March 2014, page 31). Now a collaboration led by Ignasi Ribas at the Institute of Space Sciences of Catalonia in Barcelona, Spain, and Guillem Anglada-Escudé at Queen Mary University of London has found convincing evidence of an exoplanet orbiting the Sun’s older neighbor. That exoplanet, Barnard’s Star b, is at least 3.2 times the mass of Earth and orbits the star every 233 days at a distance of about 0.4 AU.