LITHIUM ABUNDANCES OF THE SUPER-METAL-RICH OPEN CLUSTER NGC 6253

被引:32
作者
Cummings, Jeffrey D. [1 ]
Deliyannis, Constantine P. [2 ]
Anthony-Twarog, Barbara [3 ]
Twarog, Bruce [3 ]
Maderak, Ryan M. [2 ]
机构
[1] Univ Concepcion, Dept Astron, Concepcion, Chile
[2] Indiana Univ, Dept Astron, Bloomington, IN 47405 USA
[3] Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA
基金
美国国家科学基金会;
关键词
open clusters and associations: individual (NGC 6253; Hyades; M67; NGC; 3680; 752; IC; 4651); stars: abundances; techniques: spectroscopic; SOLAR-TYPE STARS; INTERNAL GRAVITY-WAVES; COSMIC-RAY NUCLEOSYNTHESIS; MAIN-SEQUENCE STARS; EVOLUTIONARY MODELS; STELLAR MODELS; HALO STARS; MICROSCOPIC DIFFUSION; CHEMICAL EVOLUTION; ANGULAR-MOMENTUM;
D O I
10.1088/0004-6256/144/5/137
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
High-resolution CTIO 4 m/HYDRA spectroscopy of the super-metal-rich open cluster NGC 6253 ([Fe/H] = +0.43 +/- 0.01) has been used to study the stellar lithium (Li) abundances near the cluster's turnoff. NGC 6253 greatly expands the range of [Fe/H] for clusters that have a Li abundance analysis. This is important for studying the complicated effects of, and potential correlations with, stellar Fe abundance on surface Li abundance. Comparisons to the younger and less-metal-rich Hyades and to the similarly aged but solar-metallicity M67 show that NGC 6253's Li abundances are qualitatively consistent with the prediction, from Standard Stellar Evolution Theory, that higher-metallicity stars have a greater Li depletion. Comparison with M67 provides evidence that the more-metal-rich NGC 6253 had a higher initial Li, which is consistent with expectations from models of Galactic Li production. NGC 6253 is also compared to the intermediate-aged NGC 3680, NGC 752, and IC 4651 open clusters. Comparison of the Li-gap positions in all six clusters shows that (1) the gap's position in T-eff is independent of metallicity, but (2) higher-metallicity clusters have their gaps in higher-mass stars. In addition, the Li gap's position is shown not to evolve with age, which provides an important constraint for the non-standard depletion mechanisms that may create the Li gap.
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页数:15
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