A census of metals and baryons in stars in the local Universe
Anna Gallazzi (1,2), Jarle Brinchmann (3), Stephane Charlot (4,2),, Simon D.M. White (2) ((1)MPIA, Heidelberg, (2)MPA, Garching, (3)CAUP, Porto,, (4) IAP, Paris)

TL;DR
This study combines galaxy spectra data from SDSS to inventory the total metals and baryons in stars in the local Universe, revealing their distribution among galaxy types and ages.
Contribution
It provides the first comprehensive estimate of the total metals and baryons in stars locally, analyzing their distribution across galaxy properties and ages.
Findings
Massive, bulge-dominated galaxies hold most metals in stars.
Bulge and disc galaxies contribute similarly to stellar mass but differently to metals.
Characteristic stellar ages decrease with galaxy mass.
Abstract
We combine stellar metallicity and stellar mass estimates for a large sample of galaxies drawn from the SDSS DR2 spanning wide ranges in physical properties, in order to derive an inventory of the total mass of metals and baryons locked up in stars today. Physical parameter estimates are derived from galaxy spectra with high S/N (>20). Coadded spectra of galaxies with similar velocity dispersions, absolute r-band magnitudes and 4000\AA-break values are used for those regions of parameter space where individual spectra have lower S/N. We estimate the total density of metals and of baryons in stars and, from these two quantities, we obtain a mass- and volume-averaged stellar metallicity of <Z_star>=1.04+-0.14 Z_sun, i.e. consistent with solar. We also study how metals are distributed in galaxies according to their mass, morphology and age, and we then compare these distributions with the…
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