An Improved Spectroscopic Analysis of DA White Dwarfs from the Sloan Digital Sky Survey Data Release 4

摘要: We present an improved spectroscopic and photometric analysis of hydrogen-line DA white dwarfs from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) based on model atmospheres that include Stark broadening profiles with non-ideal gas effects. also perform a careful visual inspection all fits high signal-to-noise ratios (S/Ns > 12) atmospheric parameters (T eff log g) for each dwarf. Through comparison temperatures, we report discovery 35 DA+DB/DC double degenerate candidates two helium-rich stars. determine cutoff at S/N = 15 optimizes size quality sample computing mean mass dwarfs, which value 0.613 M ☉. compare our results to previous analyses SDSS DR4 find good agreement if account shift produced by profiles. Finally, properties in are weighed against those Villanova White Dwarf Catalog Gianninas et al. systematically lower masses (by about 3% average), difference trace back data reduction procedure SDSS. conclude better understanding these differences will be important absolute temperature scale dwarfs.