The Te[N II]-Te[O III] temperature relation in H II regions and the
  reliability of strong-line methods
  We use a sample of 154 observations of 124 H II regions that have
measurements of both Te[O III] and Te[N II], compiled from the literature, to
explore the behaviour of the Te[O III]-Te[N II] temperature relation. We
confirm that the relation depends on the degree of ionization and present a new
set of relations for two different ranges of this parameter. We study the
effects introduced by our temperature relations and four other available
relations in the calculation of oxygen and nitrogen abundances. We find that
our relations improve slightly on the results obtained with the previous ones.
We also use a sample of 26 deep, high-resolution spectra to estimate the
contribution of blending to the intensity of the temperature-sensitive line [O
III] $\lambda4363$, and we derive a relation to correct Te[O III] for this
effect. With our sample of 154 spectra, we analyse the reliability of the R, S,
O3N2, N2, ONS, and C strong-line methods by comparing the metallicity obtained
with these methods with the one implied by the direct method. We find that the
strong-line methods introduce differences that reach ~ 0.2 dex or more, and
that these differences depend on O/H, N/O, and the degree of ionization.
