Spectroscopic Surveys
Observed mono-abundance stellar populations (MAPs) in the Milky Way disk. The plot shows the correlation between the radial scale length and the vertical scale height of MAPs, color-coded by [α/Fe]. The size of the points corresponds to the total stellar surface-mass density—corrected for mass and sample selection effects—in each population. MAPs appear to have a simple spatial structure, approximated by a single exponential in the radial and vertical directions.
MPIA/Bovy et al 2012
Spectroscopic surveys, such as SDSS-IV, provide stellar parameters, ages, and abundances.