Theoretical Examination of the Lithium Depletion Boundary
Theoretical Examination of the Lithium Depletion Boundary
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锂耗尽边界的理论检验
DOI：
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发表时间：
2003
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通讯作者：
A. Sills
中科院分区：
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作者：
C. Burke;M. Pinsonneault;A. Sills
我们探索了通过锂耗尽边界（LDB）技术获得的疏散星团年龄对恒星模型输入物理的敏感性。 LDB 年龄技术仅限于年龄在 20 到 200 Myr 之间的疏散星团。由于不确定的输入物理学，LDB 技术中的有效 1 σ 误差在最年长时约为 3%，在最年轻时增加到 8%。对于老星团和年轻星团，辐射热校正的不确定性分别给 LDB 年龄技术增加了 10% 和 6% 的误差。与观测到的昴宿星团中最快旋转体相匹配的旋转速率对 LDB 年龄的影响不到 2%。对于昴宿星团年龄的星团来说，疏散星团中的自转速率范围预计只会使 LDB 位置“模糊”0.02 星等，而对于 20 Myr 年龄的星团来说，则增加到 0.06 星等。因此，LDB 定位的观测误差 (~7%-10%) 和测辐射热校正的不确定性目前主导着 LDB 年龄的误差。对于我们的基本情况，我们正式推导出昴宿星团的 LDB 年龄为 148 ± 19 Myr，其中误差分别包括来自观测、理论和测辐射热校正源的 8%、3% 和 9% 的贡献。为了协调主序带等时线与低质量昴宿星团成员观测到的 V-I 颜色的拟合，I 波段测辐射热校正中最大合理的 0.3 星等偏移导致年龄为 126 ± 11 Myr，其中误差仅包括观测和理论误差。 LDB年龄技术排除了不包括昴宿星团对流核心超调（~75 Myr）的上部主序拟合年龄。
We explore the sensitivity in open cluster ages obtained by the lithium depletion boundary (LDB) technique to the stellar model input physics. The LDB age technique is limited to open clusters with ages ranging from 20 to 200 Myr. Effective 1 σ errors in the LDB technique due to uncertain input physics are roughly 3% at the oldest age, increasing to 8% at the youngest age. Bolometric correction uncertainties add an additional 10% and 6% error to the LDB age technique for old and young clusters, respectively. Rotation rates matching the observed fastest rotators in the Pleiades affect LDB ages by less than 2%. The range of rotation rates in an open cluster is expected to "smear" the LDB location by only 0.02 mag for a Pleiades-age cluster, increasing to 0.06 mag for a 20 Myr old cluster. Thus, the observational error of locating the LDB (~7%-10%) and the bolometric correction uncertainty currently dominate the error in LDB ages. For our base case, we formally derive an LDB age of 148 ± 19 Myr for the Pleiades, where the error includes 8%, 3%, and 9% contributions from observational, theoretical, and bolometric correction sources, respectively. A maximally plausible 0.3 mag shift in the I-band bolometric correction to reconcile main-sequence isochrone fits with the observed V-I color for the low-mass Pleiades members results in an age of 126 ± 11 Myr, where the error includes observational and theoretical errors only. Upper main sequence-fitting ages that do not include convective core overshoot for the Pleiades (~75 Myr) are ruled out by the LDB age technique.