Benjamin Roig, Michael R. Blanton, Renbin Yan

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


We infer stellar metallicity and abundance ratio gradients for a sample of red galaxies in the Sloan Digital Sky Survey (SDSS) Main galaxy sample. Because this sample does not have multiple spectra at various radii in a single galaxy, we measure these gradients statistically. We separate galaxies into stellar mass bins, stack their spectra in redshift bins, and calculate the measured absorption-line indices in projected annuli by differencing spectra in neighboring redshift bins. After determining the line indices, we use stellar population modeling from the EZ-Ages software to calculate ages, metallicities, and abundance ratios within each annulus. Our data cover the central regions of these galaxies, out to slightly higher than 1Re We find detectable gradients in metallicity and relatively shallow gradients in abundance ratios, similar to results found for direct measurements of individual galaxies. The gradients are only weakly dependent on stellar mass, and this dependence is well correlated with the change of Rewith mass. Based on these data, we report mean equivalent widths, metallicities, and abundance ratios as a function of mass and velocity dispersion for SDSS early-type galaxies, for fixed apertures of 2.5 kpc and of 0.5Re.

Original languageEnglish
Article number26
JournalAstrophysical Journal
Issue number1
StatePublished - Jul 20 2015


  • galaxies: abundances
  • galaxies: evolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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