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Metal abundances in the hottest known DO white dwarf (KPD?0005+5106)

机译：已知最热的DO白矮星中的金属丰度（KPD？0005 + 5106）

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We present the analysis of ultraviolet and optical spectra of KPD?0005+5106. Redetermination of the atmospheric parameters is necessary because the recent discovery of highly ionised metals (Ne?viii, Ca?x) indicates that the effective temperature is significantly higher than previously thought. Here we announce the discovery of lines from highly ionised silicon, sulphur, and iron (Si?vii, S?vii, Fe?x) which were never found before in any stellar photosphere. Our analysis of these lines and those from helium and several other metals gives Teff??=?200000?±?20000?K, log?g?=?6.7?±?0.3. Mass and luminosity follow from a comparison with evolutionary tracks: M?=?0.64???M⊙ and log?L/L⊙?=?3.7, so that, strictly speaking, the star is a helium-burning pre-white dwarf. The mass fractions of the metals in the helium-dominated atmosphere are in the range 0.7?4.3 solar. Hydrogen is not detectable and we derive an upper abundance limit of 0.034 solar. This abundance pattern is probably unaffected by gravitational settling and radiative levitation. Its origin lies in previous evolutionary stages. We discuss the link of KPD?0005+5106 to RCrB stars and the possibility that it results from a double-degenerate merger event.
机译：我们介绍了KPD？0005 + 5106的紫外光谱和光谱分析。重新确定大气参数是必要的，因为最近发现的高度离子化的金属（Ne？viii，Ca？x）表明有效温度明显高于以前的想法。在这里，我们宣布从高度电离的硅，硫和铁（Si？vii，S？vii，Fe？x）中发现线，这在任何恒星光球中都从未发现过。我们对这些谱线以及来自氦和其他几种金属的谱线进行分析，得出Teffδ＝≤200000±±20000≤K，log≤g≤＝ 6.7±±0.3。质量和光度是通过与演化轨迹的比较得出的：M？=？0.64 ??? M？和log？L / L ?? =？3.7，因此严格来说，该恒星是燃烧氦的预白矮星。 。在氦为主的气氛中，金属的质量分数在0.7至4.3太阳范围内。氢是不可检测的，我们得出的丰度上限为0.034太阳。这种丰度模式可能不受重力沉降和辐射悬浮的影响。它的起源在于先前的进化阶段。我们讨论了KPD？0005 + 5106与RCrB星的链接，以及它由双重简并合并事件导致的可能性。

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