Dr. Jonathan Fortney
NASA Ames

University of Florida Astronomy Colloquium - Jan 18th, 2006

New Views of the Atmospheres and Interiors of Hot Jupiters

Astronomers have now determined the masses and radii of 9 transiting extrasolar giant planets. All are in tight orbits with periods of a only a few days. Two of these planets, HD 209458b and TrES-1, have had their thermal emission detected with the Spitzer Space Telescope. I will discuss my ongoing modeling efforts to understand the atmospheres of these and other transiting planets in light of these observations. These first observations are just the start of the data that will be obtained, and coupled radiative-dynamical models likely will be needed for a more complete understanding of these atmospheres. One of the newest transiting planets, HD 149026b, is the strangest yet found. While it is more massive than Saturn, its small radius means it is composed of 60-80% heavy elements by mass, making it similar to our solar system's "ice giants" Uranus and Neptune. I will discuss thermal evolution models of this planet and compare them to models of other transiting planets. This planet receives twice the stellar irradiation of other Spitzer transiting planet targets and likely has a hot stratosphere driven by absorption of stellar flux by gaseous TiO and VO. If so, thermal emission from HD 149026b may be detectable with Spitzer.