Will we know life when we see it? The radio telescope scanned Barnard’s Star in search of extraterrestrial signals

Barnard’s Star is a small red dwarf located just six light years from Earth. Despite its proximity, it went unnoticed until 1916, when E. E. Barnard discovered that it had exceptionally high specific motion. It appeared on photographs taken by the Harvard Observatory in the late 1800s, but no one noticed it as a small, dim star. Since its discovery, Barnard’s Star has been one of the most studied red dwarf stars. Interestingly, Barnard’s Star was one of the first stars to have planets. As early as the 1970s, studies confirmed the presence of gas giants in orbit, although other observations have refuted these results. Then, in 2018, astronomers measured the star’s radial motion, suggesting the presence of a nearby super-Earth with a mass of about 3 Earths. However, other observations have refuted this finding, suggesting that the observed radial oscillations are due to solar flares. Recent studies have confirmed Barnard’s Star has no close-orbiting or potentially habitable planets larger than 70% of Earth’s size. This makes Barnard’s Star a bit unusual since most red dwarfs have planets. For example, the red dwarf star Kepler-42 is similar in size and age to Barnard’s Star and has at least three terrestrial planets. So while Barnard’s Star isn’t a strong candidate for alien life, a recent study has made detailed observations of the star, looking for any signs of an extraterrestrial signal.

The study used the Five Hundred Meter Aperture Spherical Telescope (FAST). The China Telescope is a fixed dish design similar to the Arecibo Observatory, but significantly larger. FAST is especially sensitive to frequency bands useful for long-distance communications, making it a good tool in the search for aliens. The study looked for narrow-band emissions in Barnard’s star, which is the type of signal we might see if an alien civilization intentionally directed radio messages at us. The team even focused part of their research on signals coming from the hypothetical Super-Earth Barnard’s Star b, taking into account the Doppler shift due to the relative motion between it and Earth. As expected, the study found no evidence of extraterrestrial signals. But this study is primarily a test of what FAST can do. Future studies, especially those targeting nearby stars with confirmed planets in the habitable zone, will have a higher chance of finding something.

source: https://arxiv.org/abs/2309.15377