arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1509.00513astro-ph.GA
收藏

哈勃太空望远镜自行(HSTPROMO)星系球状星团目录。III。动力学距离和质光比

Hubble Space Telescope proper motion (HSTPROMO) catalogs of Galactic globular clusters. III. Dynamical distances and mass-to-light ratios

Laura L. Watkins, Roeland P. van der Marel, Andrea Bellini, Jay Anderson

摘要:

我们提出了15个银河系球状星团的动力学距离估计,并使用这些检查动力学和光度距离估计的一致性。对于大多数集群,这是有史以来第一次确定的动态距离估计。我们使用Bellini等人(2014)最近提出的哈勃太空望远镜自行星表中的明亮恒星的清洁样本提取自行色散曲线,并从各种文献来源中编译了一组视线速度色散曲线。距离,然后估计拟合球形,非旋转,各向同性,恒定的质量与光(M/L)的动力学模型的自行车和视线色散曲线在一起。我们比较了我们的动力学距离估计与文献光度估计从哈里斯(1996年,2010年版)球状星团目录,发现这两种类型之间的平均分数差是一致的,只有$-1.9 \pm 1.7 \%$为零。这表明两种估计方法都没有明显的偏差,并为作为测光距离估计基础的恒星演化理论提供了重要的验证。分析还估计了我们的集群的动态M/L比;平均而言,动态推断的M/L比与现有的基于恒星种群的M/L比一致,假设Chabrier初始质量函数(IMF)在$-8.8 \pm 6.4 \%$内,这意味着这样的IMF与我们的数据是一致的。我们的结果也与Kroupa IMF一致,但强烈排除了Salpeter IMF。我们没有检测到我们的M/L从文献值的偏移量和我们的距离从文献值的偏移量之间的相关性,强烈表明我们的方法是可靠的,我们的结果是强大的。

英文摘要:

We present dynamical distance estimates for 15 Galactic globular clusters and use these to check the consistency of dynamical and photometric distance estimates. For most of the clusters, this is the first dynamical distance estimate ever determined. We extract proper-motion dispersion profiles using cleaned samples of bright stars from the Hubble Space Telescope proper-motion catalogs recently presented in Bellini et al. (2014) and compile a set of line-of-sight velocity-dispersion profiles from a variety of literature sources. Distances are then estimated by fitting spherical, non-rotating, isotropic, constant mass-to-light (M/L) dynamical models to the proper-motion and line-of-sight dispersion profiles together. We compare our dynamical distance estimates with literature photometric estimates from the Harris (1996, 2010 edition) globular cluster catalog and find that the mean fractional difference between the two types is consistent with zero at just $-1.9 \pm 1.7 \%$. This indicates that there are no significant biases in either estimation method and provides an important validation of the stellar-evolution theory that underlies photometric distance estimates. The analysis also estimates dynamical M/L ratios for our clusters; on average, the dynamically-inferred M/L ratios agree with existing stellar-population-based M/L ratios that assume a Chabrier initial mass function (IMF) to within $-8.8 \pm 6.4 \%$, implying that such an IMF is consistent with our data. Our results are also consistent with a Kroupa IMF, but strongly rule out a Salpeter IMF. We detect no correlation between our M/L offsets from literature values and our distance offsets from literature values, strongly indicating that our methods are reliable and our results are robust.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑