By analysing signals from the star Gliese 486, an international research team has discovered a hot rocky exoplanet with remains of a planetary atmosphere. Due to its characteristics, it is ideally suited for testing future observational methods of studying distant planetary atmospheres. The discovery of Gliese 486b, as the new planet has been named, was made possible by the CARMENES instrument. The Landessternwarte Königstuhl (LSW) of Heidelberg University is instrumental in operating this astronomical measuring device, which comprises two spectrographs.
Exoplanets are planetary bodies that are not under the gravitational influence of the Sun but under that of another star. By now, astronomers have discovered several thousand of these exoplanets. Earth-sized planets orbiting in the habitable zone of their star are of particular interest because they offer surface conditions that are capable of sustaining extragalactic life in principle.
The star Gliese 486 is located at a distance of 26 light years from Earth. Using CARMENES, the researchers measured variations in its radial velocity. Combined with data from another spectrograph at the Gemini North telescope located on Hawaii (USA) as well as the NASA space telescope TESS, the scientists discovered exoplanet Gliese 468b with ideal conditions for analysing distant planetary atmospheres. It comprises 2.8 times the mass of our home planet and orbits its star at a distance similar to the distance the Earth has to our Sun. The exoplanet’s proximity is exciting because it will become possible in future to study it in more detail with powerful new telescopes and prospective very large telescopes. This will also provide opportunities to analyse the chemical compounds within the planet’s atmosphere.
CARMENES is a novel astronomical measuring instrument designed to detect earth-like planets, particularly planets near low-mass stars like Gliese 486. It is attached to the 3.5-metre telescope of the Calar Alto Observatory near Almería in southern Spain. The highly complex instrument, consisting of two spectrographs, was developed and built by an international consortium of eleven German and Spanish institutions. Researchers from the Landessternwarte Königstuhl, which is part of the Center for Astronomy of Heidelberg University (ZAH), were significantly involved in its construction. They designed and built one of its two spectrographs and are now in charge of continuously monitoring and improving the quality of the data, which is a prerequisite for discovering earth-like planets.
T. Trifonov, J. A. Caballero, J.C. Morales et al.: A nearby transiting rocky exoplanet that is suitable for atmospheric investigation (2021), Science