Time-domain Timepieces: Inferring Precision Stellar Ages
Jennifer van Saders

Precise stellar ages have the potential to revolutionize the way we study topics ranging from exoplanets to galactochemical evolution. Stars are bright, long-lived tracers of astrophysical systems and therefore represent ideal astronomical timepieces, provided we have the means to determine their ages. However, for the vast majority of their lifetimes stars age "gracefully", limiting our ability to infer precise ages with traditional isochrone methodologies. The Kepler mission has initiated a fundamental shift in the way in which we approach the problem, with rotation and oscillations detected in large samples of stars. With proper calibration, both can be used as age indicators. I will describe our efforts to use the Kepler data to develop and validate techniques for determining ages in large populations of stars, and how that step into unexplored parameter space revealed a fundamental shift in the magnetic behavior of stars like the Sun, suggesting that our own star may be at the cusp of a transition. The result is a more nuanced understanding of the power and limitations of our age-dating techniques, and new insights into the magnetic lives of Sun-like stars.