Abstract
Some of the nearly 120 known Jupiter-mass extrasolar planets are hot Jupiters with periods less than 1-2 weeks and nearly circular orbits. Tidal interactions between these planets and their host stars lead to the circularization of their orbits and a cut off in their period distribution. In addition, it also causes planets' internal tidal heating and larger than expected sizes as inferred from the observation of a transiting planet around HD 209458.
