Abstract
Using a sample of 28 HII regions from the literature with measured
temperature inhomogeneity parameter, t^2, we present a statistical correction
to the chemical abundances determined with the direct method. We used the t^2
values to correct the oxygen gaseous abundances and consider the oxygen
depletion into dust to calculate the total abundances for these objects. This
correction is used to obtain a new calibration of Pagel's strong-line method to
determine oxygen abundances in HII regions. Our new calibration simultaneously
considers the temperature structure, the ionization structure, and the fraction
of oxygen depleted into dust grains. Previous calibrations in the literature
have included one or two of these factors; this is the first time all three are
taken into account. This recalibration conciliates the systematic differences
among the temperatures found from different methods. We find that the total
correction due to thermal inhomogeneities and dust depletion amounts to an
increase in the O/H ratio of HII regions by factors of 1.7 to 2.2 (or 0.22 to
0.35 dex). This result has important implications in various areas of
astrophysics such as the study of the higher end of the initial mass function,
the star formation rate, and the mass-metallicity relation of galaxies, among
others.
Users
Please
log in to take part in the discussion (add own reviews or comments).