论文标题
详细分析富含N的野外金属矮人样本
Detailed analysis of a sample of field metal-poor N-rich dwarfs
论文作者
论文摘要
目标。这项工作的目的是比较富含N型矮星的详细化学组成与球状簇（GC）的第二代恒星，以研究它们起源于GCS的假设。方法。我们已经测量了六个富含N金属的N型恒星的样本（其中三个是第一次指出）的23个元素（从LI到EU）的丰度，并且我们将它们的化学成分与（i）在经典金属畅通无阻的恒星样品中观察到的化学成分，以及（ii）在GCS的第二代恒星中观察到的丰度。结果。在富含金属的N型恒星中，C和O略有缺陷，但是[（C+N+O）/Fe]的散射非常小，强烈的指示表明N富集是CNO加工材料污染的结果。我们样品中的N富颗恒星，例如GC中的第二代恒星，显示出过量的Na，有时是AL的过量，如预期的那样，如果这些恒星形成的材料已被大量AGB恒星的喷射污染。我们第一次能够在NGC6752中观察到的野外恒星中建立抗相关Na-O。富含N的STAR HD 74000的金属性（EU/BA）比率相当低。在M15的几个第二代恒星中也观察到了这样的异常。结论。该分析支持以下假设：当今在田间观察到的N富集恒星是GC中的第二代恒星。
Aims. The aim of this work is to compare the detailed chemical composition of the field N-rich dwarf stars to the second generation stars of globular clusters (GC) in order to investigate the hypothesis that they originated in GCs. Methods. We have measured the abundance of 23 elements (from Li to Eu) in a sample of six metal-poor N-rich stars (three of them pointed out for the first time) and we have compared their chemical composition to, (i) the chemical composition observed in a sample of classical metal-poor stars, and (ii) the abundances observed in the second generation stars of GCs. Results. In metal-poor N-rich stars C and O are slightly deficient but the scatter of [(C+N+O)/Fe] is very small, a strong indication that the N enrichment is the result of a pollution by CNO processed material. The N-rich stars of our sample, like the second generation stars in the GCs, show an excess of Na and sometimes of Al, as expected if the material from which these stars were formed, has been polluted by the ejecta of massive AGB stars. For the first time we have been able to establish an anti-correlation Na-O in field stars like the one observed in NGC6752. The N-rich star HD 74000 has a rather low [Eu/Ba] ratio for its metallicity. Such an anomaly is also observed in several second generation stars of M15. Conclusions. This analysis supports the hypothesis that the N-rich stars today observed in the field, were born as second generation stars in GCs.
