Lucianne Walkowicz

Understanding Exoplanets in Light of their Host Stars: Stellar Astrophysics and Kepler

Although the primary purpose of NASA's Kepler mission is the discovery of exoplanets, its high precision photometry also reveals the effects of stellar magnetic activity in exquisite detail. These phenomena present on a variety of timescales, from spots that modulate the stellar brightness from days to months, to dramatic flares that evolve over a few hours. The Kepler data enable new investigations into the fundamental nature of stellar magnetism by furthering our understanding of the stellar rotation and differential rotation that generate the field, and the photometric variability caused by the surface manifestations of the field. In the case of stars with planetary candidates, these data also offer synergy between studies of stars and planets. The stellar rotation acts as a proxy for age, allowing us to place a time stamp on the planetary system, while the spot characteristics and flare rate constrain the high energy radiation input at the top of the planetary atmosphere. The Kepler data offer a new chance to not only understand the stars themselves, but to understand the range of circumstellar habitats in which planets exist. In this talk, I will discuss our ongoing work to characterize the variability due to starspots, stellar rotation and flares in the Kepler planet host stars and the larger sample of targets as a whole.