The Benchmark Cluster Reddening Project. II. A Reddening Value for M67
The Benchmark Cluster Reddening Project. II. A Reddening Value for M67
复制标题
基准集群红化项目。
DOI：
10.1086/509781
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
B. J. Taylor
中科院分区：
文献类型：
--
作者：
B. J. Taylor
自1954年以来，已经发表了70个M67的红化测定。这些结果的质量差别很大，它们只意味着星团的E（B - V）值在-0.02和+0.14 mag之间。此外，这种不确定性习惯性地被长期的引用实践所掩盖。作为回应，应用了称为“替代奖学金”的经改革的红化协议，其原则包括（1）严格的红化值的公布基础，（2）对M67的所有现存红化结果的问责制，（3）对红化技术的明确质量控制，（4）使用具有有限金属丰度灵敏度的技术，（5）对输入数据的明确零点控制（如果可能的话），（6）最终基于无尘太阳邻域的变红零点，以及（7）遵守统计规范。红化地图的结果被搁置，等待进一步检查其零点和偶然误差。此外，从颜色量值分析和从公布的红化结果的平均值得出的红化值同样被搁置。五种技术，满足所采用的协议，然后选择和应用。通过对星团A、F星和K巨星的测量结果进行平均，我们发现M67的E（B - V）平均值为41 ± 4 mmag。它还发现，现有的结果，从其他技术是一致的，这一结果，否则可以搁置合理的原因。分析产生了[Fe/H]的间接值，这与推导出的红化值一致。利用已发表的高色散数据，得到[Fe/H]的平均团簇值为-0.009 ± 0.009dex。对于M67和毕宿星团的组合，在95%的置信度下，没有发现巨星和主序附近恒星之间的平均金属丰度差异≥0.036 dex。
Since 1954, 70 reddening determinations have been published for M67. Those results are of very diverse quality, and they imply only that the value of E(B - V) for the cluster lies between -0.02 and +0.14 mag. In addition, this uncertainty is habitually concealed by long-standing citation practices. In response, a reformed reddening protocol called "alternative scholarship" is applied, with tenets including (1) rigorous published foundations for reddening values, (2) accountability for all extant reddening results for M67, (3) explicit quality control of reddening techniques, (4) use of techniques with limited metallicity sensitivity, (5) explicit zero-point control of input data (when possible), (6) a reddening zero point based ultimately on the dust-free solar neighborhood, and (7) adherence to statistical norms. Results from reddening maps are then set aside pending further examination of their zero points and accidental errors. In addition, reddening values derived from color-magnitude analysis and from averages of published reddening results are likewise set aside. Five techniques that satisfy the adopted protocol are then selected and applied. By averaging results from cluster A and F stars and K giants, one finds that the mean value of E(B - V) for M67 is 41 ± 4 mmag. It is also found that extant results from additional techniques are consistent with this result or else can be set aside for plausible reasons. The analysis yields a collateral value of [Fe/H], and this is consistent with the derived reddening value. Using published high-dispersion data, it is found that the mean cluster value of [Fe/H] is -0.009 ± 0.009 dex. For M67 and the Hyades combined, no mean metallicity difference between giants and stars near the main sequence is found that is ≥0.036 dex at 95% confidence.