Publication
The Homogeneity of the Star-forming Environment of the Milky Way Disk over Time
Publisher:
American Astronomical Society
Date:
02-2022
DOI:
10.3847/1538-4357/AC4754
Abstract: Stellar abundances and ages afford the means to link chemical enrichment to galactic formation. In the Milky Way, in idual element abundances show tight correlations with age, which vary in slope across ([Fe/H]–[ α /Fe]). Here, we step from characterizing abundances as measures of age, to understanding how abundances trace properties of stellar birth environment in the disk over time. Using measurements from ∼27,000 APOGEE stars ( R = 22,500, signal-to-noise ratio 200), we build simple local linear models to predict a s le of elements (X = Si, O, Ca, Ti, Ni, Al, Mn, Cr) using (Fe, Mg) abundances alone, as fiducial tracers of supernovae production channels. Given [Fe/H] and [Mg/H], we predict these elements, [X/H], to about double the uncertainty of their measurements. The intrinsic dispersion, after subtracting measurement errors in quadrature is ≈0.015–0.04 dex. The residuals of the prediction (measurement − model) for each element demonstrate that each element has an in idual link to birth properties at fixed (Fe, Mg). Residuals from primarily massive-star supernovae (i.e., Si, O, Al) partially correlate with guiding radius. Residuals from primarily supernovae Ia (i.e., Mn, Ni) partially correlate with age. A fraction of the intrinsic scatter that persists at fixed (Fe, Mg), however, after accounting for correlations, does not appear to further discriminate between birth properties that can be traced with present-day measurements. Presumably, this is because the residuals are also, in part, a measure of the typical (in)-homogeneity of the disk’s stellar birth environments, previously inferred only using open cluster systems. Our study implies at fixed birth radius and time that there is a median scatter of ≈0.01–0.015 dex in elements generated in supernovae sources.