A sample of metal-poor galaxies identified from the LAMOST spectral survey

We present a sample of 48 metal-poor galaxies at z < 0.14 selected from 92 510 galaxies in the LAMOST survey. These galaxies are identified by their detection of the auroral emission line[OⅢ]λ4363 above the 3σ level, which allows a direct measurement of electron temperature and oxygen abundance. The emission line fluxes are corrected for internal dust extinction using the Balmer decrement method. With electron temperature derived from [OⅢ]λλ4959, 5007/[OⅢ]λ4363 and electron density from [SⅡ]λ6731/[SⅡ]λ6717, we obtain the oxygen abundances in our sample which range from 12 + log(O/H) = 7.63(0.09 Z⊙) to 8.46(0.6 Z⊙). We find an extremely metal-poor galaxy with 12 + log(O/H) = 7.63 ± 0.01. With multiband photometric data from FUV to NIR and Hαmeasurements, we also determine the stellar masses and star formation rates, based on the spectral energy distribution fitting and Hα luminosity, respectively. We find that our galaxies have low and intermediate stellar masses with 6.39 ≤ log(M/M⊙) ≤ 9.27, and high star formation rates(SFRs) with-2.18 ≤ log(SFR/M⊙yr-1) ≤ 1.95. We also find that the metallicities of our galaxies are consistent with the local Te-based mass–metallicity relation, while the scatter is about 0.28 dex. Additionally,assuming the coefficient of α = 0.66, we find most of our galaxies follow the local mass–metallicity–SFR relation, but a scatter of about 0.24 dex exists, suggesting the mass–metallicity relation is weakly dependent on SFR for those metal-poor galaxies.