NGC1316的球状星团系统。I.华盛顿系统中的宽视场测光
The globular cluster system of NGC1316. I. Wide-field photometry in the Washington system
摘要：
NGC 1316（天炉座A）是天炉座星系团外围的一个突出的合并残留物。集群系统尚未得到全面研究。因此，我们提出了一个广泛的领域研究的球状星团系统的NGC 1316，调查其性质的关系，全球的NGC 1316的形态。我们使用了CTIO的4米布兰科望远镜上的MOSAIC II相机，在华盛顿C和哈里斯R的滤光片中。我们确定了球状星团的候选者，并研究了它们的颜色分布和系统的结构特性。在附录中，我们还作了形态学的评论，目前的彩色地图，并提出了新的模型的亮度和颜色的星系配置文件。星系团系统被很好地限制在NGC 1316的光学可见外轮廓。整个样本的颜色分布是单峰的，但在凸起明亮的子样本的颜色分布显示出两个峰值，通过与太阳金属丰度的理论华盛顿颜色比较，分别对应于约2 Gyr和0.8 Gyr的年龄。我们还发现了在0.8 < C-R < 1.1的颜色范围内有大量的星团，这些星团必须由小于0.8 Gyr的星团组成，除非它们非常缺乏金属。颜色区间1.3 < C-R < 1.6是大部分中间年龄星团的所在地，这些星团的表面密度分布在约4弧分处急剧下降。外集群人口显示出单峰的颜色分布，在C-R=1.1的峰值，表明旧的，金属贫乏的集群的贡献较大。它们的光度函数并没有显示出预期的转变，所以年轻星团的比例仍然很重要。NGC 1316的团簇形成在最初的爆发后仍在继续，推测与主合并有关。一个玩具模型与两个爆发的年龄2 Gyr和0.8 Gyr是一致的光度特性和动态M/L值。
英文摘要：
NGC 1316 (Fornax A) is a prominent merger remnant in the outskirts of the Fornax cluster. The cluster system has not yet been studied in its entirety. We therefore present a wide-field study of the globular cluster system of NGC 1316, investigating its properties in relation to the global morphology of NGC 1316. We used the MOSAIC II camera at the 4-m Blanco telescope at CTIO in the filters Washington C and Harris R. We identify globular cluster candidates and study their color distribution and the structural properties of the system. In an appendix, we also make morphological remarks, present color maps, and present new models for the brightness and color profiles of the galaxy. The cluster system is well confined to the optically visible outer contours of NGC 1316. The color distribution of the entire sample is unimodal, but the color distribution of bright subsamples in the bulge shows two peaks that, by comparison with theoretical Washington colors with solar metallicity, correspond to ages of about 2 Gyr and 0.8 Gyr, respectively. We also find a significant population of clusters in the color range 0.8 < C-R < 1.1 which must be populated by clusters younger than 0.8 Gyr, unless they are very metal-poor. The color interval 1.3 < C-R < 1.6 hosts the bulk of intermediate-age clusters which show a surface density profile with a sharp decline at about 4 arcmin. The outer cluster population shows an unimodal color distribution with a peak at C-R=1.1, indicating a larger contribution of old, metal-poor clusters. Their luminosity function does not show the expected turn-over, so the fraction of younger clusters is still significant. Cluster formation in NGC 1316 has continued after an initial burst, presumably related to the main merger. A toy model with two bursts of ages 2 Gyr and 0.8 Gyr is consistent with photometric properties and dynamical M/L-values.
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