Cranmer, S. R., "Planet-Star Interactions: Magnetic Fields and Winds," April 19, 2010, Harvard-Smithsonian CfA ITC (Institute for Theory and Computation) Monday Pizza Lunch Talk.
There is growing observational evidence for some kind of interaction between stars and close-in extrasolar giant planets. Almost a decade ago, Shkolnik et al. began reporting variability in the chromospheric Ca H and K lines of HD 179949 and upsilon And that seemed to be phased with the planet's orbital period, instead of the stellar rotational period. Work here at the CfA has extended the observational evidence to X-rays, but all existing measurements are plagued by the fact that these signatures do not repeat exactly from orbit to orbit. Despite the fact that I'm an exoplanet dabbler, I will endeavor to give an overview of the physical processes that we believe are occurring in these planet-star interactions, and how they might eventually be used to diagnose the properties of the winds/coronae of the host stars, as well as the magnetospheres of the planets.
Shkolnik, E., Aigrain, S., Cranmer. S., Fares, R., Fridlund, M., Pont, F., Schmitt, J., Smith, A., and Suzuki, T. 2009, "Star-Planet Interactions," 15th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, St. Andrews, Scotland, July 21-25, 2008 (Splinter Session Summary Paper), AIP Conf. Ser. 1094, p. 275. [arXiv preprint: arXiv:0809.4482]
Cranmer, S. R., and Saar, S. H. 2008, "Exoplanet-Induced Chromospheric Activity: Realistic Light Curves from Solar-type Magnetic Fields," 14th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Pasadena, CA, November 6-10, 2006 (Poster), ASP Conf. Ser. 384, ed. G. van Belle, CD-ROM. [arXiv preprint: astro-ph/0702530]