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The ages and metallicities of galaxies in the local universe


This page contains the DR4 version of the tables referenced in "The ages and metallicities of galaxies in the local universe" by Gallazzi et al (2005), see also "Ages and metallicities of early-type galaxies in the Sloan Digital Sky Survey: new insight into the physical origin of the colour-magnitude and the Mg2V relations", Gallazzi et al (2006). Any use of these data should reference at least Gallazzi et al (2005). The table contain the full set of objects, 567486, and is matched to the star formation, gas-phase metallcity and raw data tables provided on this site. Please see the papers for details about the determination of these quantities and any caveats that should be kept in mind when using these data.

Note that the stellar metallicities given in the catalogue are not in solar units. To have them in solar units, as in Gallazzi et al 2005, subtract log(Zsun=0.02) from the values in the catalogue.

A note on the mass estimates

We note that for galaxies already present in the DR2 data release there have been small changes in the measured magnitudes (but not in the absorbtion line indices). While stellar metallicities and ages are only mildly affected by this, the stellar masses derived using DR4 photometry show an offset of <~0.1dex with respect to the stellar masses based on DR2 photometry. This happens for a subset of galaxies which show a similar offset in their z-band model magnitudes (which we use to normalize the stellar mass-to-light ratio). We provide here also stellar masses based on the z-band Petrosian magnitudes, which do not suffer from any systematic difference between DR2 and DR4 data releases. "Petrosian" stellar masses are on average lower than "model" stellar masses by about 0.1dex. This reflects the fact that Petrosian magnitudes recover about 80 percent of the flux for a de Vaucouleurs profile, while model magnitudes are (extrapolated) total magnitudes.

Stellar metallicities

This table contains the estimates of stellar metallicities with the columns having the following meaning:

Fortran format: format(1x,i5,1x,i8,1x,i5,6(1x,f10.4))

  column  1: plate ID
  column  2: MJD
  column  3: fiber ID
  column  4: 2.5 percentile of likelihood distribution of
             stellar metallicity
  column  5: 16 percentile
  column  6: median of likelihood distribution of 
             stellar metallicity (log Z)
  column  7: 84 percentile
  column  8: 97.5 percentile
  column  9: mode of the distribution
  column 10: The index (starting at 0) into the SDSS data files.

Download the catalogue here - gzipped text file.

r-band weighted ages

This table contains the estimates of r-band weighted ages with the same format and the same meaning of the columns as for the stellar metallicity catalogue. The units are log yr.

Download the catalogue here

Stellar mass estimates

This table contains the estimates of the stellar mass in units of log solar mass from the model fits. As noted above there are two mass estimates available, one based on model magnitudes and one based on Petrosian magnitudes.

Download the mass estimates based on z-band Petrosian magnitudes here

Download the mass estimates based on z-band Model magnitudes here

Last modified: Sat May 24 13:47:07 CEST 2008