New methods to measure stellar parameters and Galactic rotation

Ralph Schoenrich

Ohio State University

Obtaining accurate and unbiased stellar distances is essential for measuring Galactic kinematics and structure. I will shortly discuss the different statistical methods we have at hand to assess distance calibrations and will show their application in deriving a distance calibration for Blue Horizontal Branch stars in the Galactic halo. With these distances we have determined halo rotation with different methods, finding no significant rotation both for the entire Galactic halo and for subsamples in metallicity or Galactocentric radius.

In the second part I will show our new approach to Bayesian stellar parameter determination, which seeks an optimal exploitation of prior knowledge, photometry and spectral information to derive consistent expectation values and errors for the metallicities, temperatures, gravities, distances, etc. of stars. This method has been successfully applied to high resolution data and SEGUE/SDSS data.