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SUMMARY:Abiotic Ozone in the Observable Atmospheres of Venus-like Planets 
 - Robb Calder / IoA
DTSTART:20241204T131500Z
DTEND:20241204T134000Z
UID:TALK225148@talks.cam.ac.uk
CONTACT:Xander Byrne
DESCRIPTION:Ozone is a potential exoplanet biosignature due to its associa
 tion with photosynthetically produced oxygen and strong absorption in the 
 mid-infrared. However\, the existence of ozone in Venus’s observable atm
 osphere\, a planet with no known life\, raises the possibility of ozone bi
 osignature false-positives on Venus-like exoplanets. We use a photochemica
 l model of Venus’s atmosphere to investigate the origin of its mesospher
 ic ozone layer\, and how similar ozone layers would manifest for Venus-lik
 e exoplanets. Our model shows that the hypothesis that Venus’s ozone for
 ms on the nightside due to a flux of O radicals from the dayside\, cannot 
 generate enough ozone to match observed levels. Furthermore\, we show that
  sufficient ozone cannot be produced by varying the surface chemistry\, at
 mospheric thermal structure\, or stellar flux in our model of Venus’s at
 mosphere\, implying that a presently unknown chemical pathway is responsib
 le for the ozone in Venus’s mesosphere. Until the origin of Venus’s oz
 one is understood\, we cannot rule out that ozone production will be commo
 n on abiotic Venus-like worlds\, a possibility that limits the usefulness 
 of ozone as a biosignature.
LOCATION:The Hoyle Lecture Theatre + Zoom 
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