关于0 Z项目的更新
An Update on the 0Z Project
摘要：
通过对Hamburg/ESO巡天数据库的挖掘，更新了我们的0 Z巡天数据库，寻找更多的[Fe/H] < -3 dex的极贫金属（EMP）星。我们提出了最极端的这样的恒星，我们发现从~1550中等分辨率的后续光谱。其中之一，HE 1424 -0241，具有高度异常的丰度比，在任何以前已知的晕巨星中都没有发现，非常缺乏Si，中度缺乏Ca和Ti，高度增强Mn和Co，以及低C，所有相对于Fe。我们建议SNII的爆炸性α燃烧核的核合成产率是非常低的相比，流体静力学α燃烧元素镁，这是正常的，在这颗星相对于铁。第二个，不太极端，离群星与高[Sc/Fe]也被发现。我们检查的HES金属丰度分布函数的极贫金属的尾巴（E1）。根据我们的高分辨率详细丰度分析结果与[Fe/H]（HES）的比较，我们认为，候选EMP星的HES样品的后续谱中，[Fe/H]（HES）<-3dex时，由HES样品推断的丰度受到严重污染;许多低于该金属丰度的假设EMP恒星具有相当高的Fe金属丰度，包括大多数非常富C的恒星，或者是虚假对象。
英文摘要：
We give an update on our 0Z Survey to find more extremely metal poor (EMP) stars with [Fe/H] < -3 dex through mining the database of the Hamburg/ESO Survey. We present the most extreme such stars we have found from ~1550 moderate resolution follow up spectra. One of these, HE1424-0241, has highly anomalous abundance ratios not seen in any previously known halo giant, with very deficient Si, moderately deficient Ca and Ti, highly enhanced Mn and Co, and low C, all with respect to Fe. We suggest a SNII where the nucleosynthetic yield for explosive alpha-burning nuclei was very low compared to that for the hydrostatic alpha-burning element Mg, which is normal in this star relative to Fe. A second, less extreme, outlier star with high [Sc/Fe] has also been found. We examine the extremely metal-poor tail of the HES metallicity distribution function (MDF). We suggest on the basis of comparison of our high resolution detailed abundance analyses with [Fe/H](HES) for stars in our sample that the MDF inferred from follow up spectra of the HES sample of candidate EMP stars is heavily contaminated for [Fe/H](HES) < -3 dex; many of the supposed EMP stars below that metallicity are of substantially higher Fe-metallicity, including most of the very C-rich stars, or are spurious objects.
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