Princeton University Extrasolar Planet Discussion Group

The interiors of Exo-Saturns are among the most diverse of any class of planet.  Objects with the same mass and insolation can range in radius by more than a factor of two!  Even among the cooler planets, the metallicity can run essentially the whole range from 0 to 100% (roughly).  Furthermore, hot Saturns rarely have surface gravities less than 3 m/s2 even though structure models of such planets are readily produced.  For this talk, I will discuss my recent progress in understanding these objects.  In particular, I will argue that hot Saturns of sufficiently low gravity can experience cataclysmic runaway mass loss under the right conditions, and explain why this effect has not been well-discussed in the past.  I will also show my results for the compositions of the cooler Saturns, which show a clear jump between the metal rich and poor objects, which is a potential signature of runaway gas accretion during formation.