A LITHIUM-RICH RED GIANT BELOW THE CLUMP IN THE KEPLER CLUSTER, NGC 6819
A LITHIUM-RICH RED GIANT BELOW THE CLUMP IN THE KEPLER CLUSTER, NGC 6819
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DOI：
10.1088/2041-8205/767/1/l19
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发表时间：
2013-03
期刊：
影响因子：
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通讯作者：
B. Anthony-Twarog;C. Deliyannis;Evan A. Rich;B. Twarog
中科院分区：
文献类型：
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作者：
B. Anthony-Twarog;C. Deliyannis;Evan A. Rich;B. Twarog
旧疏散星系团NGC6819的332个可能成员在Li6708ä区获得了WIYN/HYDRA光谱。初步分析表明，从岔道顶部到巨型分支底部，锂元素呈亏损模式。从低于星团水平1毫克开始，所有较亮的巨星的A(Li)都低于1.0，其中大多数的上限低于0.5。位于第一次上升的红巨星凸起下方的恒星W007017富锂，A(Li)=2.3。作为一种极有可能的单星天体测量和径向速度星系团成员，其不同的星震成员可能是引发LI增强的过程的副产品。它的颜色-星等图的位置与第一次上升的红巨星之间只有一次提出的增强混合过程一致。
WIYN/HYDRA spectra in the Li 6708 Å region have been obtained for 332 probable members of the old open cluster, NGC 6819. Preliminary analysis shows a pattern of Li depletion from the top of the turnoff to the base of the giant branch. Starting 1 mag below the level of the clump, all brighter giants have A(Li) below 1.0, with most having upper limits below 0.5. Star W007017, located below the first-ascent red giant bump is Li-rich with A(Li) = 2.3. As a highly probable single-star astrometric and radial-velocity cluster member, its discrepant asteroseismic membership could be a by-product of the processes that triggered Li enhancement. Its color–magnitude diagram location is consistent with only one proposed enhanced mixing process among first-ascent red giants.