Poster Abstracts

Name/Affiliation:  Jennifer van Saders (Ohio State University)

Title:  Gyrochronology in Context: Rotation and Age for Realistic Stellar Populations

Abstract:
The technique of gyrochronology uses the observed relationship between rotation period, stellar color, and age to date old field stars based on two key assumptions: 1) that all targets can be treated as single main sequence stars that spin down as a function of time, and 2) that the relations can be calibrated on systems of solar age and younger and extrapolated to old stars, where data has traditionally been sparse. We examine the validity of each of these assumptions. Realistic stellar populations are not composed solely of single dwarfs, but contain several backgrounds: we theoretically predict that hot stars, synchronized binaries, and subgiants should all obey very different period-age relationships than cool, single, main sequence stars. We use data from the Kepler satellite and population models to demonstrate that these “background” sources are significant in number, and confirm that they do not obey the standard relationship between period and age. Accounting for them is therefore critical for proper population modeling. We also use a sample of old Kepler field stars with measured periods and independent asteroseismic ages to critically evaluate the performance of gyrochronology extrapolations against the actual behavior of stars at late times.