An article (link to PDF file) published in the journal “Nature” describes the discovery of a possible super-Earth orbiting the Barnard’s Star, a red dwarf that in astronomical terms is in the neighborhood being about 6 light years away from the Earth. The Red Dots and CARMENES projects led to the discovery of what was named Barnard’s Star b and could be the second exoplanet closest to the solar system after Proxima b.

Barnard’s Star has already been the object of research in the hope of finding exoplanets that orbit it exactly because it’s the star closest to the Sun after Alpha Centauri’s triple system but so far the results were negative. The observations of Barnard’s Star were also studied by the projects Red Dots and CARMENES (Calar High high-resolution search for Mdwarfs with Exoearths with Near-infrared and optical Échelle Spectrographs), which try to discover Earth-like planets that orbit red dwarfs.

The possible super-Earth in the Barnard’s star’s system was discovered through one of the indirect techniques used for exoplanet research, the radial velocity method. It’s the first time that it’s used to detect a rocky exoplanet with such a large orbit around its star as the variations it causes in its star’s position and speed are very small.

In the case of the exoplanet Barnard’s Star b, the researchers collected a considerable amount of data from the archives of various instruments collected in the course of research conducted over the years. In particular, the HARPS (High Accuracy Radial velocity Planet Searcher) spectrometer was important due to its remarkable accuracy in that type of measurements.

The result is that Ignasi Ribas of the Institute of Space Studies of Catalonia and the Institute of Space Sciences, CSIC, Spain, stated that his team is 99% confident that the planet is there. These are still indirect detections so the researchers intend to keep on observing Barnard’s Star’s movements to obtain certainty ruling out other possible causes in the variations detected.

Data analysis indicates that Barnard’s Star b has a mass of about 3.2 times the Earth’s and its year lasts about 233 Earth days. Even if it’s a super-Earth and is relatively close to the solar system, the only reasons for enthusiasm are scientific because that exoplanet is probably not very hospitable. Its distance from Barnard’s Star is similar to that of Mercury from the Sun but the red dwarf is cold so the energy that the planet receives was estimated at around 2% of what the Earth receives from the Sun.

In essence, the exoplanet Barnard’s Star b seems like a cold place, with temperatures on its surface that could be around -150° Celsius. Perhaps it’s more similar to a giant version of Mars than the Earth or perhaps a giant version of Titan, Saturn’s great moon with hydrocarbon lakes where there are chemical reactions despite the cold. In these cases there are many questions and very few answers but each research can bring progress in exoplanet research with the possibility of discovering more neighbors.