However, other teams were unable to confirm, and by the 1970s we knew the discovery was merely a product of defective instruments. Scientists kept looking at the star, and now astronomers from the Institute of Space Studies of Catalonia and the Institute of Space Sciences in Spain have assembled 20 years of data to reveal Barnard’s Star b. The newly published study lays out the basics of the exoplanet.
Barnard’s Star b completes an orbit of the star every 233 Earth days. It’s about as far away from Barnard’s Star as Mercury is from Earth, but Barnard’s Star is much cooler. So, it’s distinctly outside the habitable zone with a surface temperature of -170 degrees Celsius (-274 degrees Fahrenheit). It’s the equivalent of a planet orbiting between Mars and Jupiter in our solar system.
Barnard’s Star b has a mass about three times that of Earth, but we don’t know its size or composition yet. We suspect it’s rocky, though. Barnard’s Star b does not transit in front of its host star from Earth’s perspective — that would have made detection vastly simpler. Instead, the team used the radial velocity method. They watched for small counter movements in the star that indicate a massive body (a planet) is in orbit.
A smaller star like Barnard’s Star wobbles more than a more massive one, so even a small-ish planet like this one had some detectable effect. The team claims high confidence that Barnard’s Star b is real, but other teams will need to confirm. We don’t want another van de Kemp scenario.