标题： 老年疏散星团 NGC 6791 的高分辨率红外光谱学 显示英文标题

标题： High resolution infrared spectroscopy of the old open cluster NGC6791

摘要： 我们基于凯克II望远镜的NIRSPEC光谱仪（1.5-1.8微米）在R=25,000的红外光谱，对古老疏散星团NGC6791中的6颗M型巨星成员进行了丰度分析。我们发现铁丰度<[Fe/H]>=+0.35±0.02，证实了之前通过光学中高分辨率光谱得出的超太阳金属丰度。我们也测量了碳(C)、氧(O)和其他α元素的丰度，发现大致为太阳的[α/Fe]和<[C/Fe]>=-0.35。我们的方法特别有效地限制了[O/Fe]，基于在近1.6微米处测量到的多个OH线，我们得到[O/Fe]=-0.07±0.03。与银河系核球中相似恒星的成分相比，这种太阳系α元素的增强形成对比。我们还发现低12C/13C~10，证实了在红巨星演化阶段存在额外混合过程，甚至达到超太阳金属丰度。 显示英文摘要

摘要： We report abundance analysis for 6 M giant members of the old open cluster NGC6791, based on infrared spectroscopy (1.5-1.8 micron) at R=25,000, using the NIRSPEC spectrograph at the Keck II telescope. We find the iron abundance <[Fe/H]>= +0.35 +/- 0.02$, confirming the super solar metallicity of this cluster derived from optical medium-high resolution spectroscopy. We also measure C, O and other alpha element abundances, finding roughly solar [alpha/Fe] and <[C/Fe]> = -0.35. Our approach constrains [O/Fe] especially well, based on the measurement of a number of OH lines near 1.6micron; we find [O/Fe]=-0.07 +/-0.03. The Solar alpha enhancement is in contrast to the composition of similar stars in the Galactic bulge. We also find low 12C/13C~10, confirming the presence of extra-mixing processes during the red giant phase of evolution, up to super solar metallicities.