Calar Alto Observatory discovers a super-Earth in the second closest star system to Earth

Only six light-years, Barnard's star moves in the night sky from Earth faster than any other star. This red dwarf, smaller and older than our Sun., is among red dwarf less active known, thus it is representing an ideal target to search for exoplanets. Now, An international team of researchers has found a cold super-Earth orbiting around the star Barnard, the second closest star system to Earth. Is the first time astronomers discover such exoplaneta using the method of the radial velocity. The results, CARMENES obtained with the instruments of Calar Alto Observatory, They published in the journal Nature.

"After a thorough analysis, we are sure to 99% that the planet is there, since this is the model that best fits our observations ", says study leader, Ignasi Ribas, CSIC researcher at the Institute of Space Sciences and the Institute of Space Studies of Catalonia. "But nevertheless, we must be cautious and collect more data to confirm the finding, because natural variations in brightness caused by the star sunspots could produce similar effects to the detected ".


The subtle wobble of the star has attracted the attention of astronomers long. From 1997 Several instruments have incorporated a lot of measurements on the oscillatory movement. An analysis of 2015 Wade suggested that might be caused by a planet with an orbital period of about two hundred and thirty days. But more measurements are required.

Trying to confirm the hypothesis, astronomers have observed regularly Barnard's star through high precision spectrometers CARMENES, at the Calar Alto Observatory. The technique is to use the doppler effect on starlight to measure how the speed of an object in our line of sight changes over time.

"With the radial velocity method, spectrometers are used to accurately measure the effect doppler. When an object moves away from us, the light we observe becomes slightly less energetic and more red. Unlike, when the star is approaching us, the light becomes more energetic and blue ", Ribas says.

"Rescanning all the combined measures, He appeared a clear signal over a period of two hundred thirty-three days. This signal means that Barnard's star is approaching and moving away from us at about 1.2 meters per second, roughly the speed of a person walking- and the best explanation for this phenomenon is that a planet is orbiting the star ", Ribas says.

The candidate planet, star called Barnard b (he GJ 699 b), is a super-Earth with minimal 3,2 landmasses. Orbits its red star every two hundred thirty-three days near the snowline, a distance at which water freezes. Lacking atmosphere, it is likely that its temperature is -170, making it unlikely that the planet may have liquid water on the surface.

"No exoplanet so small and so far away from its star had previously discovered by doppler technique", Ribas says. This means that astronomers are getting better at finding and exploring a relatively new type of planets outside the Solar System.

"We have worked very hard to get this result", Research indicates Guillem Anglada-Escudé, Queen Mary University of London, and co-director of the study. "This is the result of a collaboration organized in the context of the project Red Dots, collaborations bringing together teams from around the world, including semi-professional astronomers coordinated by the AAVSO ", adds.

Cristina Rodriguez-López, researcher at the Institute of Astrophysics of Andalusia (IAA, CSIC) and coauthor of the study, He believes that "this discovery means a boost to continue the search for exoplanets orbiting our stellar neighbors, hoping that eventually find one that has the right conditions to support life ".

The Hispano-German Astronomical Observatory of Calar Alto is located in the Sierra de Los Filabres, Northern Almería (Andalusia, Spain). It is operated jointly by the Max-Planck Institute for Astronomy one Heidelberg, Germany, and Institute of Astrophysics of Andalusia (CSIC) in Granada, Spain. The observatory is a Singular Scientific Technical Infrastructure (ICTS/MINECO) which it has four telescopes 3.5, 2.2, 1.23 and 0,8 meter aperture.