your ID: 0297 
First Name: shaoying 
Last Name: yin 
National Astronomical Observatories, 
Chinese Academy of Sciences 

Title: Empirical Strong-line Oxygen Abundance Calibrations from 
Galaxies with Electron Temperature Measurements 
Authors: Shaoying Yin, Yanchun Liang, F.Hammer, J.Brinchmann, 
Bo Zhang, Licai Deng, and H.Flores 
Topic: 9 
Session: poster 
Abstract: We have selected 531 star-forming galaxies from the  Fourth 
Data Release of the Sloan Digital Sky Survey database (SDSS-DR4) with
 strong emission lines, including [OIII]4363) detected at a signal-to-noise 
larger than 5\\sigma, as well as 164 galaxies from  the literature with existing 
Te measurements. O/H abundances have been derived from a two-zone 
model for the temperature structure, assuming a relationship between high 
ionization and low ionization species. 
The comparison between the (O/H)_{Te} and the Bayesian estimates from 
the MPA/JHU group show that, for almost half of the sample galaxies, metallicities 
were overestimated by about 0.34\\,dex on average, which may be due to the treatment 
for the onset of N enrichment in the Charlot\'s models used in the SDSS. R_{23} and 
P-method systematically overestimate the O/H abundance by a factor of \\sim0.20\\,dex 
and \\sim0.06\\,dex, respectively. The N2 index provides more consistent O/H abundances 
with Te-method, but with a large scatter. The relations of N2, O3N2, S2 with 
log(O/H) are consistent with the photoionization model calculations.  We derive analytical 
calibrations for O/H from N2, O3N2 and S2 indices on the basis of this 
large sample of galaxies, as well including the hardness of the ionization as an additional 
parameter for the N2 index. These allow us to circumvent the systematic offsets between 
indirect O/H calibration and that from the Te method, although keeping a 
relatively large scatter.