DEATH OF A CLUSTER: THE DESTRUCTION OF M67 AS SEEN BY THE SLOAN DIGITAL SKY SURVEY
DEATH OF A CLUSTER: THE DESTRUCTION OF M67 AS SEEN BY THE SLOAN DIGITAL SKY SURVEY
复制标题
DOI：
10.1088/0004-637x/711/2/559
复制
发表时间：
2010-01
期刊：
影响因子：
--
通讯作者：
J. Davenport;E. Sandquist
中科院分区：
文献类型：
--
作者：
J. Davenport;E. Sandquist
我们使用斯隆数字巡天第六次数据发布的测光数据来探测老疏散星团M67的空间和动力学结构。利用最佳对比度，或匹配滤波器，算法，我们映射M67的高概率成员的分布。我们发现了一个延伸和拉长的晕圈，半径接近60′。我们测得的核心半径Rcore = 8.′24 ± 0.′60比以前的估计值稍大。我们将更大的核心半径测量归因于SDSS探测的质量较低的主序星比以前对M67的类似研究所做的要低，以及在SDSS样本中排除了后主序星M67成员。我们估计SDSS样本中M67成员的数量为1385 ± 67颗恒星。在M67中的二进制分数的下限被测量为45%。在核心中测得的双星比例比在晕中测得的要高，并且发现核心的光度函数中低质量恒星的含量更低。因此，晕是一致的集群内的质量偏析。M67的银河系轨道是根据最近的自行和径向速度测定计算的。拉长的晕大致与星系团的自行一致。这似乎是由于银河系潮汐场造成的质量分离的结果。我们的算法运行在2微米全天巡天光度直接比较以前的研究M67。发现质量较大的恒星的核心半径逐渐减小。我们测试我们的算法使用1000人工簇蒙特卡罗模拟的准确性。研究发现，匹配滤波技术是适合于恢复低密度的空间结构，以及测量的二进制分数的集群。
We probe the spatial and dynamical structure of the old open cluster M67 using photometric data from the Sloan Digital Sky Survey's sixth data release. Making use of an optimal contrast, or matched filter, algorithm, we map the distribution of high probability members of M67. We find an extended and elongated halo of likely members to a radius of nearly 60′. Our measured core radius of Rcore = 8.′24 ± 0.′60 is somewhat larger than that of previous estimates. We attribute the larger core radius measurement to the SDSS probing lower mass main sequence stars than has been done before for similar studies of M67, and the exclusion of post-main-sequence M67 members in the SDSS sample. We estimate the number of M67 members in our SDSS sample to be 1385 ± 67 stars. A lower limit on the binary fraction in M67 is measured to be 45%. A higher fraction of binary stars is measured in the core as compared to the halo, and the luminosity function of the core is found to be more depleted of low-mass stars. Thus, the halo is consistent with mass segregation within the cluster. The galactic orbit of M67 is calculated from recent proper motion and radial velocity determinations. The elongated halo is roughly aligned to the proper motion of the cluster. This appears to be a result of mass segregation due to the galactic tidal field. Our algorithm is run on Two Micron All Sky Survey photometry to directly compare to previous studies of M67. Decreasing core radii is found for stars with greater masses. We test the accuracy of our algorithm using 1000 artificial cluster Monte Carlo simulations. It is found that the matched filter technique is suitable for recovering low-density spatial structures, as well as measuring the binary fraction of the cluster.