Wednesday 28 Sep 2016: Beyond the Standard Model: Precision Stellar Physics in the Era of Surveys and Space Missions
Prof. Marc Pinsonneault - Ohio State University
Physics, 4th Floor 14:00-15:00
Stellar astrophysics is being revolutionized by large scale surveys. Time domain surveys from space and the ground, designed to detect extrasolar planets, have resulted in tens of thousands of stellar oscillation and rotation measurements. High-resolution spectroscopic surveys have yielded hundreds of thousands of high quality measurements, and the Gaia mission promises the release of enormous volumes of astrometric data. We are now in a position to critically test the theory of stellar structure and evolution and to make detailed kinematic, abundance, and age maps of the Milky Way galaxy. In this talk I will focus on the sea change in our understanding of stellar rotation and on the prospects for rotation as a viable age diagnostic for stellar populations. I will demonstrate that there appear to be intrinsic environmental differences in rotation between star forming regions, in the sense that dense clusters appear to have a larger rapid rotator population. K2 observations in the Pleiades reveal strong correlations between rotation and the presence of binary companions and confirm a striking transition in rotation between solar-like and low mass stars. Asteroseismology both permits the measurement of core rotation rates in evolved stars and precise ages for field stars, which in turn allows us to test the validity of rotation-age relationships (gyrochronology) for stars less active than the Sun. We find striking evidence that stellar spin down stalls at the activity level of the Sun. Combined with measurements of differential rotation with depth and latitude in stars, the solar rotation pattern is revealed to be somewhat of a special case. I will close with a worked example of rotation in Kepler field stars, demonstrating both the complications in interpreting field star rotation rates and the path forward for precision stellar astrophysics.