Four small planets discovered around one of the closest stars to Earth – an expert explains what we know
Barnard’s Star is a small, dim star, of the type that astronomers call red dwarfs. Consequently, even though it is one of the closest stars to Earth, such that its light takes only six years to get here, it is too faint to be seen with the naked eye. Now, four small planets have been found orbiting the star. Teams in America and Europe achieved this challenging detection by exploiting precision instruments on the world’s largest telescopes. Diminutive Barnard’s Star is closer in size to Jupiter than to the Sun. Only the three stars that make up the Alpha Centauri system lie closer to us. The planets newly discovered around Barnard’s Star are much too faint to be seen directly, so how were they found? The answer lies in the effect of their gravity on the star. The mutual gravitational attraction keeps the planets in their orbits, but also tugs on the star, moving it in a rhythmic dance that can be detected by sensitive spectrograph instruments. Spectrographs split up the star’s light into its …
