Since it was launched seven years ago, Carmenes has not stopped looking for planets Earth-like outside the Solar System. Now, the scientists of this international project have counted up: between 2016 and 2020 they have discovered 59 exoplanets, ten potentially habitable.
Carmenes is not only the name of the scientific project, it is also the name of the main instrument, a spectrometer installed in the 3.5 meter telescope from the Calar Alto Observatory in Almería and financed by the Higher Council for Scientific Research and the Max Planck Society of Germany.
This instrument, which measures both visible and infrared light Of the objects it analyses, it looks for rocky planets (or exo-Earths) with conditions to harbor liquid water and, therefore, life.
After several years of work, the scientific team, made up of more than 200 researchers of eleven German and Spanish institutions and co-led by the Institute of Astrophysics of Andalusia (IAA), with the participation of the Institute of Space Sciences (IEEC-CSIC), and the Center for Astrobiology (CAB), has just published all the information on the project.
The article, which has been published in the journal ‘Astronomy & Astrophysics’, includes data from 20,000 measurements to 362 nearby cool stars.
“Carmenes was a risky bet by the CSIC and the Max Plank Society, which financed the project, but today we know not only that it has been revolutionary and pioneering, but that it is also obtaining great results,” Ignasi Ribas, director of the Institut d’Estudis Espacials de Catalunya (IEEC) and main author of the compilation.
This is how Carmenes works
To detect planets, Carmenes uses the ‘Doppler’ method or radial velocity measurement technique, capable of measure speeds in stars with extreme precision, “of the order of one meter per second, which is the speed of a person walking”, explains Ribas.
In this way, the technique allows find small planets around low mass stars. Although other scientific teams have used this method since the mid-1990s, Carmenes has been the first to use radial velocity to study red dwarfs, fainter and cooler than the Sun, “and a type of star that needs to be observe on a different wavelength,” he says.
Since then, Carmenes has studied 17 known planets and has discovered another 59 planets close to the Solar System but “with a very interesting plus: Carmenes studies the coldest stars and, therefore, are at a shorter distance from the Solar System”, that is, it allows discovering the planets that are closer to us, “those that in the future we are going to be able to study in detail”.
“Especially Nice” Finds
In these years, the project has made some “particularly nice” finds, such as the two planetary systems around the stars of Teegarden and GJ 1002, with two planets each of a mass similar to that of the Earth and orbiting a red dwarf in its habitable zone, that is, in conditions that “if they had water it could be liquid “.
But with Carmenes the astronomers too They have found out a lot. “We have observed that, in general, there are few giant planets around small stars. Small stars tend to have small planets, although there are notable exceptions,” comments Ribas.
An example is the star GJ-3512 which has two huge planets. about the size of Jupiter. “We still don’t know how such a tiny star could have formed two such large planets. It is a mystery and one of the great discoveries of Carmenes,” recalls the researcher.
For Ribas all These results support the importance of a project that “has put Calar Alto and its researchers on the world map of the search for exoplanets. Now we are reaping the fruits of all this top-quality science,” he stresses.
Carmenes will continue to observe stars until the end of this year and, later, “what is desirable” is that the project be extended again to continue with these studies “beyond 2023”, concludes Ribas.