The role of cold gas and environment on the stellar mass - metallicity
  relation of nearby galaxies
  We investigate the relationship between stellar mass, metallicity and gas
content for a magnitude- and volume-limited sample of 260 nearby late-type
galaxies in different environments, from isolated galaxies to Virgo cluster
members. We derive oxygen abundance estimates using new integrated, drift-scan
optical spectroscopy and the base metallicity calibrations of Kewley & Ellison
(2008). Combining these measurements with ultraviolet to near-infrared
photometry and HI 21 cm line observations, we examine the relations between
stellar mass, metallicity, gas mass fraction and star formation rate. We find
that, at fixed stellar mass, galaxies with lower gas fractions typically also
possess higher oxygen abundances. We also observe a relationship between gas
fraction and metal content, whereby gas-poor galaxies are typically more
metal-rich, and demonstrate that the removal of gas from the outskirts of
spirals increases the observed average metallicity by approximately 0.1 dex.
Although some cluster galaxies are gas-deficient objects, statistically the
stellar-mass metallicity relation is nearly invariant to the environment, in
agreement with recent studies. These results indicate that internal
evolutionary processes, rather than environmental effects, play a key role in
shaping the stellar mass-metallicity relation. In addition, we present
metallicity estimates based on observations of 478 nearby galaxies.
