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SUMMARY:A new perspective on the Habitable Zone: a smooth function of stel
 lar and planetary properties - Andras Zsom (MIT)
DTSTART:20140806T153000Z
DTEND:20140806T163000Z
UID:TALK53628@talks.cam.ac.uk
CONTACT:Dr B.-O. Demory
DESCRIPTION:The surface climate of rocky exoplanets is influenced by a lar
 ge number of stellar\, and planetary properties most of which are currentl
 y unconstrained. Our empirical knowledge of small planets around small sta
 rs is limited to the stellar properties\, planet radius\, and incoming ste
 llar flux. Although this information is necessary to constrain the surface
  climate\, they alone are insufficient to do so. My goal is to quantify wh
 at we know about liquid water bearing planets (the Habitable Zone) based o
 n our current observational knowledge. To do that\, I use a statistical ap
 proach to synthesize a large number of planet scenarios and I study the su
 bset of the population that harbors liquid water on the surface. The appro
 ach treats stellar and planetary properties as random variables each with 
 their respective probability density function (PDF). Some variables are ob
 servationally constrained (e.g.\, incoming stellar flux and planet radius)
 . Others remain unconstrained to date (e.g.\, atmospheric composition\, su
 rface albedo) and I adopt various PDFs for such variables. The method allo
 ws me to investigate what fraction of planets could harbor liquid water as
  a function of planet radius and incoming stellar flux. I find that based 
 on our current observational knowledge\, the probability that an Earth-lik
 e exoplanet (a planet with one Earth radius and an incoming stellar flux o
 f one solar constant) harbors liquid water is between 0% and 70%. The prob
 ability is strongly influenced by the PDFs of surface pressure and atmosph
 eric composition. Thus\, the constraints will be stronger once these prope
 rties are better known.
LOCATION:Martin Ryle Seminar Room\, Kavli Institute
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