New fully empirical calibrations of strong-line metallicity indicators
  in star forming galaxies
  We derive new empirical calibrations for strong-line diagnostics of gas phase
metallicity in local star forming galaxies by uniformly applying the Te method
over the full metallicity range probed by the Sloan Digital Sky Survey (SDSS).
To measure electron temperatures at high metallicity, where the auroral lines
needed are not detected in single galaxies, we stacked spectra of more than
110,000 galaxies from the SDSS in bins of log[O II]/H$\beta$ and log[O
III]/H$\beta$. This stacking scheme does not assume any dependence of
metallicity on mass or star formation rate, but only that galaxies with the
same line ratios have the same oxygen abundance. We provide calibrations which
span more than 1 dex in metallicity and are entirely defined on a consistent
absolute Te metallicity scale for galaxies. We apply our calibrations to the
SDSS sample and find that they provide consistent metallicity estimates to
within 0.05 dex.
