Strong RR Lyrae excess in the Hercules-Aquila Cloud
Strong RR Lyrae excess in the Hercules-Aquila Cloud
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DOI：
10.1093/mnras/stu133
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发表时间：
2014-01
影响因子：
4.8
通讯作者：
I. Simion;V. Belokurov;M. Irwin;Sergey E. Koposov
中科院分区：
文献类型：
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作者：
I. Simion;V. Belokurov;M. Irwin;Sergey E. Koposov
我们使用卡塔利纳巡天报告的~ 14，000 RR天琴座的精确3D位置来绘制银河系恒星晕中的大尺度子结构。在10-25 kpc的日心距离范围内，在天空中大约由30{\deg} < l < 55{\deg}和-45{\deg} < B < -25{\deg}界定的区域内，似乎有大量的RRa B星。这种高密度，峰值在18千秒差距，最有可能与所谓的武仙座-天鹰座云有关，之前使用斯隆数字巡天数据中类似距离的主序列示踪剂检测到。我们对该地区RR型天琴座的周期-振幅分布的分析表明，HAC以Oosterhoff I型种群为主。通过比较测量的RR天琴座数密度的平滑恒星晕的模型，我们估计的意义所观察到的过剩，并提供一个更新的估计的总光度的云的祖。
We map the large-scale sub-structure in the Galactic stellar halo using accurate 3D positions of ~14,000 RR Lyrae reported by the Catalina Sky Survey. In the heliocentric distance range of 10-25 kpc, in the region of the sky approximately bounded by 30{\deg} < l < 55{\deg} and -45{\deg} < b < -25{\deg}, there appears to be a strong excess of RRab stars. This overdensity, peaking at 18 kpc, is most likely associated with the so-called Hercules-Aquila Cloud, previously detected using Main Sequence tracers at similar distances in the Sloan Digital Sky Survey data. Our analysis of the period-amplitude distribution of RR Lyrae in this region indicates that the HAC is dominated by the Oosterhoff I type population. By comparing the measured RR Lyrae number density to models of a smooth stellar halo, we estimate the significance of the observed excess and provide an updated estimate of the total luminosity of the Cloud's progenitor.