距离银河系中心90千秒差距的造父变星
Clustered Cepheid Variables 90 kiloparsec from the Galactic Center
摘要：
靠近我们银河系平面的遥远区域很大程度上没有被光学探测到，因为它们被尘埃所掩盖。我们使用了来自ESO公共调查VISTA Via Lactea（VVV）的近红外数据（最大限度地减少尘埃遮蔽）（Minniti et al. 2011; Saito et al. 2012;此后称为S12）来搜索低纬度的遥远恒星。我们已经发现了四颗造父变星，它们的中心位于银河经度$l = -27.4^\circ$和银河纬度$b = -1.08 ^\circ$，角度范围为一度。我们使用这些脉动恒星所遵循的严格约束的周期-光度关系（Wavesson et al. 2004; Matsunaga et al. 2011）来推导距离。我们推断这些造父变星的平均距离为90 kpc。造父变星在角度（一度以内）和距离（距离的标准差为12 kpc）上高度聚集。它们与平面的平均距离为$\sim 2~\rm kpc$，最大投影间距为$\sim 1~ \rm kpc$。这些年轻的（$\sim$ 1亿年）脉动恒星（Bono et al. 2005）与银河系盘的距离如此之大是出乎意料的，银河系盘终止于$\sim$ 15 kpc（Minniti et al. 2011）。造父变星在距离和角度上的高度聚集性表明，这些恒星可能与一个矮星系有关，这是早期通过动力学分析预测的（Chakrabarti \& Blitz 2009）。
英文摘要：
Distant regions close to the plane of our Galaxy are largely unexplored by optical surveys as they are hidden by dust. We have used near-infrared data (that minimizes dust obscuration) from the ESO Public survey VISTA Variables of the Via Lactea (VVV) (Minniti et al. 2011; Saito et al. 2012; henceforth S12) to search for distant stars at low latitudes. We have discovered four Cepheid variables within an angular extent of one degree centered at Galactic longitude of $l = -27.4^\circ$ and Galactic latitude of $b = -1.08 ^\circ$. We use the tightly constrained period-luminosity relationship that these pulsating stars obey (Persson et al. 2004; Matsunaga et al. 2011) to derive distances. We infer an average distance to these Cepheid variables of 90 kpc. The Cepheid variables are highly clustered in angle (within one degree) and in distance (the standard deviation of the distances is 12 kpc). They are at an average distance of $\sim 2~\rm kpc$ from the plane and their maximum projected separation is $\sim 1~ \rm kpc$. These young ($\sim$ 100 Myr old), pulsating stars (Bono et al. 2005) are unexpected at such large distances from the Galactic disk, which terminates at $\sim$ 15 kpc (Minniti et al. 2011). The highly clustered nature in distance and angle of the Cepheid variables suggests that the stars may be associated with a dwarf galaxy, one that was earlier predicted by a dynamical analysis (Chakrabarti \& Blitz 2009).
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。
