Two Classes of Exoplanets Identified Without Modeling

Abstract:  The Spitzer Space Telescope has measured numerous eclipses of exoplanets, and ground-based telescopes and Hubble are now getting into the game.  These measurements give the planetary flux in the observation filter.  In combination with the planetary radius, known from transit, one can determine a brightness temperature, Tb.  I compare these Tbs with the planets' predicted equilibrium temperatures, Teq, calculated assuming zero albedo and uniform reradiation of absorbed energy from the entire planetary surface. Measurements deviate from the simplistic Teq prediction because of the chemistry and temperatures present in the atmosphere, but other effects like clouds may play important roles as well.  By comparing Tb and Teq, and without reference to any interpretive model, I have identified two distinct classes of exoplanets, with cooler exoplanets having similar Tb and Teq while hotter exoplanets have higher Tb than Teq.  I will discuss possible explanations, such as thermal inversions, clouds, and competing radiative and convective time constants.

I currently have a funded but unoccupied graduate student position in my group to work on this project.  Rising seniors interested in a PhD in planetary science are encouraged to attend, and to speak with me sooner about the possibility of PhD study at UCF.  I am visiting Cornell through August 2.