标题： 最近在SDSS中发现的DB间隙白矮星的非局部热平衡光谱分析 显示英文标题

标题： Non-LTE spectral analyses of the lately discovered DB-gap white dwarfs from the SDSS

摘要： 长期以来，没有已知的氢缺乏白矮星的有效温度在30 kK和小于45 kK之间，即高于DB型白矮星的有效温度而低于DO型白矮星的有效温度。 因此，这一温度范围长期以来被称为DB空隙。 直到最近，SDSS提供了几个DB空隙候选星的光谱。 基于局部热动平衡（LTE）假设下计算的模型光谱的第一批分析证实了这些恒星的有效温度在30 kK和45 kK之间（Eisenstein等人，2006年）。 对于DO型白矮星的研究已经表明，需要放松LTE假设以解释大气中由强烈辐射场引起的非局部效应。 因此，我们计算了一个非LTE模型网格，并重新分析了上述SDSS光谱集。 我们的结果确认了DB空隙白矮星的存在。 显示英文摘要

摘要： For a long time, no hydrogen-deficient white dwarfs have been known that have effective temperature between 30 kK and < 45 kK, i.e. exceeding those of DB white dwarfs and having lower ones than DO white dwarfs. Therefore, this temperature range was long known as the DB-gap. Only recently, the SDSS provided spectra of several candidate DB-gap stars. First analyses based on model spectra calculated under the assumption of local thermodynamic equilibrium (LTE) confirmed that these stars had 30 kK < Teff < 45 kK (Eisenstein et al. 2006). It has been shown for DO white dwarfs that the relaxation of LTE is necessary to account for non local effects in the atmosphere caused by the intense radiation field. Therefore, we calculated a non-LTE model grid and re-analysed the aforementioned set of SDSS spectra. Our results confirm the existence of DB-gap white dwarfs.