Free Astronomy Magazine September-October 2021

49 SEPTEMBER-OCTOBER 2021 ASTRO PUBLISHING tronomer at the Centre for Astrobi- ology in Madrid, Spain, and one of the authors of the study published in Astronomy & Astrophysics . The results are an important step in the quest to find life on Earth-sized planets outside the Solar System. The detection of biosignatures on an exoplanet depends on the ability to study its atmosphere, but current telescopes are not large enough to achieve the resolution needed to do this for small, rocky planets. The newly studied planetary system, called L 98-59 after its star, is an at- tractive target for future observa- tions of exoplanet atmospheres. Its orbits a star only 35 light-years away and has now been found to host rocky planets, like Earth or Venus, which are close enough to the star to be warm. With the contribution of ESO’s VLT, the team was able to infer that three of the planets may contain water in their interiors or atmos- pheres. The two planets closest to the star in the L 98-59 system are probably dry, but might have small amounts of water, while up to 30% of the third planet’s mass could be water, making it an ocean world. Furthermore, the team found “hid- den” exoplanets that had not previ- ously been spotted in this planetary system. They discovered a fourth planet and suspect there is a fifth, in a zone at the right distance from the star for liquid water to exist on its surface. “We have hints of the pres- ence of a terrestrial planet in the habitable zone of this system,” ex- plains Olivier Demangeon, a re- searcher at the Instituto de Astro- física e Ciências do Espaço, Univer- sity of Porto in Portugal and lead au- thor of the new study. The study represents a technical breakthrough, as astronomers were able to determine, using the radial velocity method, that the innermost T his artist’s impression shows L 98-59b, one of the planets in the L 98-59 sys- tem 35 light-years away. The system con- tains four confirmed rocky planets with a potential fifth, the furthest from the star, being unconfirmed. [ESO/M. Kornmesser]