Milky Way disk kinematics

At MPIA Galaxy coffee, there were great talks about the Milky Way disk by Gail Zasowski (JHU) and Jonathan Bird (Vanderbilt). Zasowski showed results on the kinematics of the MW disk ISM based on diffuse interstellar bands. She used the three-d dust map from Schlafly et al to figure out the mean distance to each absorber, and sees a consistent story. Bird showed that the age–metallicity relationship in the disk (briefly, that older stars have higher velocity dispersion) is a product not just of disk heating but also of disk formation, if the disks form in the cosmological context as expected. Late in the day, Bird and I (with help from Rix) formulated a way to measure the age–metallicity relationship and its dependence on Galactocentric radius via a likelihood function (and therefore Bayes). We vowed to try to do this with the APOGEE data plus stellar ages from Ness's recent work with The Cannon.