A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood
A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood
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DOI：
10.1093/mnras/stv1981
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发表时间：
2015-08
影响因子：
4.8
通讯作者：
C. Bell;E. Mamajek;Tim Naylor University of Rochester;U. Exeter
中科院分区：
文献类型：
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作者：
C. Bell;E. Mamajek;Tim Naylor University of Rochester;U. Exeter
我们利用内勒和杰弗里斯在M_V，V-J色星等图中的tau^2最大似然拟合统计量，基于半经验主序前模型等时线的齐次拟合，提出了一个太阳附近年轻（<2亿年）、邻近（< 100 pc）运动星系群的自洽绝对等时年龄标度。最后通过的年龄组为：AB Dor移动星群149+51-19百万年，{\beta} Pic移动星群（BPMG）24+/-3百万年，Carina星群45+11-7百万年，Columba星群42+6-4百万年，{\eta} Cha星群11+/-3百万年，Tucana-Horologium移动星群（Tuc-Hor）45+/-4百万年，TW Hya群为10+/-300万年，32 Ori群为22+4- 300万年。在这个阶段，我们不太愿意给阿古斯星协一个最终的、明确的年龄，因为我们的成员名单似乎受到了高度的污染，因此还不清楚这些恒星是否代表了同一时期的恒星。我们的等时年龄的BPMG和Tuc-Hor与最近的锂耗尽边界（LDB）的年龄，不像等时年龄，是相对不敏感的低质量的进化模型的选择是一致的。这种一致性之间的等时线和LDB年龄灌输的信心，我们的自我一致，绝对年龄尺度年轻，附近的移动组是强大的，因此，我们建议，这些年龄为这些群体的未来研究。实施本研究中描述的方法的软件可从http：//www.astro.ex.ac.uk/people/timn/tau-squared/获得。
We present a self-consistent, absolute isochronal age scale for young (< 200 Myr), nearby (< 100 pc) moving groups in the solar neighbourhood based on homogeneous fitting of semi-empirical pre-main-sequence model isochrones using the tau^2 maximum-likelihood fitting statistic of Naylor & Jeffries in the M_V, V-J colour-magnitude diagram. The final adopted ages for the groups are: 149+51-19 Myr for the AB Dor moving group, 24+/-3 Myr for the {\beta} Pic moving group (BPMG), 45+11-7 Myr for the Carina association, 42+6-4 Myr for the Columba association, 11+/-3 Myr for the {\eta} Cha cluster, 45+/-4 Myr for the Tucana-Horologium moving group (Tuc-Hor), 10+/-3 Myr for the TW Hya association, and 22+4-3 Myr for the 32 Ori group. At this stage we are uncomfortable assigning a final, unambiguous age to the Argus association as our membership list for the association appears to suffer from a high level of contamination, and therefore it remains unclear whether these stars represent a single population of coeval stars. Our isochronal ages for both the BPMG and Tuc-Hor are consistent with recent lithium depletion boundary (LDB) ages, which unlike isochronal ages, are relatively insensitive to the choice of low-mass evolutionary models. This consistency between the isochronal and LDB ages instills confidence that our self-consistent, absolute age scale for young, nearby moving groups is robust, and hence we suggest that these ages be adopted for future studies of these groups. Software implementing the methods described in this study is available from http: //www.astro.ex.ac.uk/people/timn/tau-squared/.