Tues 2/25: James Davenport: Spots and Flares: Detailed Studies of Magnetic Activity with Kepler
Spots and Flares: Detailed Studies of Magnetic Activity with Kepler
University of Washington
Tuesday, February 25, 2014
12:30pm CAS 500
Photometry from the Kepler mission has revealed the presence of cool starspots and hot flares on the surfaces of thousands of main sequence stars. These light curve features are manifestations of magnetic fields, and modeling their properties and evolution over time reveals fundamental information about the strength and nature of the stellar dynamo. I will show results from detailed studies of flares and starspots for a small number of active stars. GJ 1243, a rapidly rotating M4 star, has frequent flares with a rate of nearly one per hour. We have amassed the largest catalog of flares for any single star (besides the Sun), which we use to statistically understand the rise and decay profile of flares. GJ 1243 also possesses a remarkably stable polar starspot spanning more than three years of observation. A secondary starspot is also seen, with an evolution timescale of ~100 days. Using the relative positions of these spots on the stellar surface, we have determined the differential rotation rate which is one of the slowest ever measured. In addition, modeling starspot properties for stars with planetary transits allows us to break degeneracies between spot size, latitude, and contrast. I will discuss our efforts to model three of these transiting systems from Kepler with a wide range of rotation periods and spot properties.