论文标题
GAIA-ESO调查：球状群集NGC 1261中的一个极为充实的巨人
The Gaia-ESO Survey: an extremely Li-rich giant in the globular cluster NGC 1261
论文作者
论文摘要
球状簇中富含锂的恒星很少见。实际上，到目前为止，只有14个在从矮人到巨人的不同进化阶段发现。已经提出了不同的机制来解释这种增强，但这仍然是一个空旷的问题。使用在ESO非常大的望远镜上使用长颈鹿光谱仪获得的Gaia-Eso调查中收集的光谱，我们介绍了在RED GIANT BRANCH BUMP阶段中闻名的第二个星团NGC 1261中发现的第一颗Li-rich恒星。恒星显示（li）_lte = 3.92 \ pm0.14的极端li过度，对应于（li）_nlte = 3.40 dex。我们建议LI增强是由额外的混合过程（有时称为{\ em凉爽的底部燃烧}）引起的，或者可能是二进制质量转移导致的液体过高，这可能是由于红色巨型分支星星的含量，因为稀有钡的丰度低。但是，要明确解释球状簇星中的LI增强，但是，需要可靠地确定Be，6Li，12c/13c等关键物种的丰度，以及需要几个S过程元素，以及详细的色体活性指标的建模。
Lithium rich stars in globular clusters are rare. In fact, only 14 have been found so far, in different evolutionary phases from dwarfs to giants. Different mechanisms have been proposed to explain this enhancement, but it is still an open problem. Using spectra collected within the Gaia-ESO Survey, obtained with the GIRAFFE spectrograph at the ESO Very Large Telescope, we present the discovery of the first Li-rich star in the cluster NGC 1261, the second star known in the red giant branch bump phase. The star shows an extreme Li overabundance of A(Li)_LTE=3.92\pm0.14, corresponding to A(Li)_NLTE=3.40 dex. We propose that the Li enhancement is caused by fresh Li production through an extra mixing process (sometimes referred to as {\em cool bottom burning}) or could be a pre-existing Li overabundance resulting from binary mass transfer, likely from a red giant branch star, because of the low barium abundance. To unambiguously explain the Li enhancement in globular cluster stars, however, a reliable determination of the abundance of key species like Be, 6Li, 12C/13C, and several s-process elements is required, as well as detailed modeling of chromospheric activity indicators.
