BEGIN:VCALENDAR VERSION:2.0 PRODID:-//AIP Calendar//www.aip.de// BEGIN:VEVENT SUMMARY:Colloquium: Anna Shapiro (Max Planck Institute for Solar System Re search) | 21.03.2023 DTSTART:20240321T133000Z DTEND:20240321T150000Z DTSTAMP:20260407T113353Z UID:www.aip.de-1692 CATEGORIES:Scientific CATEGORIES:Generic Event CATEGORIES:Public CONTACT:Julián Alvarado-Gómez DESCRIPTION:Metal-rich stars are less friendly to life: The UV paradox\nAb stract: While the ozone is only a minor component of the Earth’s atmosph ere\, it is one of the most important species to sustain life on the Earth . It is produced photochemically from molecular oxygen. Both oxygen and oz one protects the biosphere by absorbing harmful UV radiation. In this stud y we address the intriguing question of what would happen with the ozone l ayer if the Earth is hosted by another solar-like star instead of the Sun. Namely\, we model the atmosphere of an ExoEarth orbiting a solar-like sta r with different values of metallicity (from -1 to 1 dex) and effective te mperature (from 5300 to 6300 K). We show that\, paradoxically\, although m etal-rich stars emit less UV radiation than metal-poor stars\, the drop of ozone concentration leads to higher surface UV on their planets. This imp lies that the Universe gets less life friendly as it ages because stars be come more metal-rich. We also study the response of the ozone layer and su rface UV to different disturbing factors such as increase of stellar magne tic activity\, supernova explosion\, volcanic eruptions. We found that whi le volcanic eruptions are the most ozone destructive hazards\, oxidised at mospheres (O2 level higher than 20%) have sufficient buffering capacity t o reduce the damage. Furthermore\, our calculations indicate that recently proposed events of sudden rise of stellar magnetic activity lead to incre ase in ozone concentration and\, consequently\, drop in the surface UV.\n LOCATION:Schwarzschildhaus Lecture Hall END:VEVENT END:VCALENDAR