Thermal Tides: An Explanation for the Inflated Radii of the Hot Jupiters

As a newly discovered class of astrophysical objects, the hot Jupiters provides some clearly-posed, but difficult to explain, physical problems. The inferred radii of transiting hot Jupiters are far too large to be explained by internal heating due to passive gravitational contraction. A subtle tidal mechanism resulting from asymmetric day-night heating, known as "thermal tides," leads to asynchronous spin in the steady state. The ongoing dissipation of the gravitational tide provides the necessary internal dissipation required to inflate hot Jupiters for the lifetime of the system. The basic physics of thermal tides in gas giant fluid planets as well as a description of how this mechanism may be important in understanding the observed properties of the hot Jupiters will be given.