一颗47 Tuc AGB星相对于大角星的化学丰度差分析
Differential chemical abundance analysis of a 47 Tuc AGB star with respect to Arcturus
摘要：
这项研究解决了在47 Tuccenda渐近巨星分支恒星Lee 2525中Zr丰度的差异。这颗恒星是用赛丁泉天文台2.3米望远镜的中阶梯摄谱仪观测到的。分析是通过校准Lee 2525相对于标准巨星大角星进行的。这项工作强调了使用标准恒星的重要性，其恒星参数与分析中的恒星相当，而不是相对于太阳进行校准（Koch & McWilliam 2008）。由于标准星和程序星之间大气结构的相似性，分析过程中的系统误差被最小化。除Zr外，Lee 2525的丰度与Brown & Wallerstein（1992）的值基本一致。在这项研究中，Zr与另一种轻s-过程元素Y（[Y/Fe]=+0.53 dex）具有类似的增强（[Zr/Fe] =+0.51 dex），这反映了当前关于AGB星内核过程富集s-过程元素的理论（Busso et al. 2001）。这与Brown & Wallerstein（1992）的结果相反，其中相对于Fe，Zr是不充足的（[Zr/Fe] = +0.51 dex），而Y是过量的（[Y/Fe] = +0.50 dex）。
英文摘要：
This study resolves a discrepancy in the abundance of Zr in the 47 Tucanae asymptotic giant branch star Lee 2525. This star was observed using the echelle spectrograph on the 2.3 m telescope at Siding Spring Observatory. The analysis was undertaken by calibrating Lee 2525 with respect to the standard giant star Arcturus. This work emphasises the importance of using a standard star with stellar parameters comparable to the star under analysis rather than a calibration with respect to the Sun (Koch & McWilliam 2008). Systematic errors in the analysis process are then minimised due to the similarity in atmospheric structure between the standard and programme stars. The abundances derived for Lee 2525 were found to be in general agreement with the Brown & Wallerstein (1992) values except for Zr. In this study Zr has a similar enhancement ([Zr/Fe] = +0.51 dex) to another light s-process element, Y ([Y/Fe] = +0.53 dex), which reflects current theory regarding the enrichment of s-process elements by nuclear processes within AGB stars (Busso et al. 2001). This is contrary to the results of Brown & Wallerstein (1992) where Zr was under-abundant ([Zr/Fe] = +0.51 dex) and Y was over-abundant ([Y/Fe] = +0.50 dex) with respect to Fe.
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