Lithium Abundances of the Super-metal-rich Open Cluster NGC 6253
Abstract
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.
- Publication:
-
The Astronomical Journal
- Pub Date:
- November 2012
- DOI:
- 10.1088/0004-6256/144/5/137
- arXiv:
- arXiv:1209.5758
- Bibcode:
- 2012AJ....144..137C
- Keywords:
-
- open clusters and associations: individual: NGC 6253 Hyades M67 NGC 3680 NGC 752 IC 4651;
- stars: abundances;
- techniques: spectroscopic;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- doi:10.1088/0004-6256/144/5/137