We select 947 star-forming galaxies from SDSS-DR7 with [O~{\sc iii}]4363 emission lines detected at a signal-to-noise {ratio }larger than 5. Their electron temperatures and direct oxygen abundances are {then }determined. {W}e compare the results from different methods. {, the} electron temperature in {the }low ionization region{,} estimated from {, that} in {the }high ionization region{,} {is} compared {using} three analysis relations between {. These} show obvious differences, which result in some different ionic oxygen abundances. The results of , , {/} and {/} derived by using methods from IRAF and literature are also compared. The ionic abundances / {are} higher than / for most cases. The{ different} oxygen abundances derived from and the strong-line ratios show {a }clear discrepancy, which is more obvious following increasing stellar mass and strong-line ratio . The sample{ of} galaxies from SDSS {with} detected [O~{\sc iii}]4363 have lower metallicites and higher {star formation rates}, {so} they may not be typical representatives of the whole{ population of} galaxies. Adopting data objects from {Andrews & Martini}, {Liang et al.} and {Lee et al.} data, we derive new relations of stellar mass and metallicity for star-forming galaxies in a much wider stellar mass range: from to .

生成讲解博客的中文版本

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