Metal Abundances of KISS Galaxies. VI. New Metallicity Relations for the
  KISS Sample of Star-Forming Galaxies
  We present updated metallicity relations for the spectral database of
star-forming galaxies (SFGs) found in the KPNO International Spectroscopic
Survey (KISS). New spectral observations of emission-line galaxies (ELGs)
obtained from a variety of telescope facilities provide oxygen abundance
information. A nearly four-fold increase in the number of KISS objects with
robust metallicities relative to our previous analysis provides for an
empirical abundance calibration to compute self-consistent metallicity
estimates for all SFGs in the sample with adequate spectral data. In addition,
a sophisticated spectral energy distribution (SED) fitting routine has provided
robust calculations of stellar mass. With these new and/or improved galaxy
characteristics, we have developed luminosity-metallicity ($L$-$Z$) relations,
mass-metallicity ($M_{*}$-$Z$) relations, and the so-called Fundamental
Metallicity Relation (FMR) for over 1,450 galaxies from the KISS sample. This
KISS $M_{*}$-$Z$ relation is presented for the first time and demonstrates
markedly lower scatter than the KISS $L$-$Z$ relation. We find that our
relations agree reasonably well with previous publications, modulo modest
offsets due to differences in the SEL metallicity calibrations used. We
illustrate an important bias present in previous $L$-$Z$ and $M_{*}$-$Z$
studies involving direct-method ($T_{e}$) abundances that may result in
systematically lower slopes in these relations. Our KISS FMR shows consistency
with those found in the literature, albeit with a larger scatter. This is
likely a consequence of the KISS sample being biased toward galaxies with high
levels of activity.
