The Virgo Overdensity Explained
The Virgo Overdensity Explained
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DOI：
10.3847/1538-4357/ab4f72
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
Thomas Donlon;Heidi Jo Newberg;J. Weiss;P. Amy;Jeffery M. Thompson
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文献类型：
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作者：
Thomas Donlon;Heidi Jo Newberg;J. Weiss;P. Amy;Jeffery M. Thompson
我们认为，在恒星晕中的室女座恒星密度过高是径向矮星系合并的结果，我们称之为室女座径向合并。由于矮星系非常接近银河系中心，碎片具有很大的能量范围，但Lz角动量几乎为零。碎片似乎从室女座区域的太阳延伸5至50千秒差距。我们将这种合并碎片的不同移动群连接到周流和平行流（室女座星流与这两个流中的一个或两个相关），武仙座-天鹰座云，可能还有波江座-凤凰座高密度。这种径向合并可以解释大多数观测到的天琴座RR和蓝色水平分支恒星的移动群，这些恒星以前在室女座被发现。这种合并也会在太阳附近产生类似于盖亚-土卫二合并或盖亚香肠的碎片。轨道提供了室女座辐射合并的祖先和碎片的组成部分，似乎是有关的Cocytos流，这也是在室女座地区恢复。
We suggest that the Virgo Overdensity of stars in the stellar halo is the result of a radial dwarf galaxy merger that we call the Virgo Radial Merger. Because the dwarf galaxy passed very near to the Galactic center, the debris has a large range of energies but nearly zero Lz angular momentum. The debris appears to extend from 5 to 50 kpc from the Sun in the Virgo region. We connect different moving groups of this merger debris to the Perpendicular and Parallel Streams (the Virgo Stellar Stream is associated with either or both of these streams), the Hercules-Aquila Cloud, and possibly the Eridanus-Phoenix Overdensity. This radial merger can explain the majority of the observed moving groups of RR Lyrae and blue horizontal branch stars that have previously been identified in Virgo. This merger also produces debris in the solar neighborhood similar to that identified as the Gaia–Enceladus merger or Gaia sausage. Orbits are provided for components of the Virgo Radial Merger progenitor and debris that appears to be related to the Cocytos Stream, which was also recovered in the Virgo region.