Piercing the Milky Way: an all-sky view of the Orphan Stream
Piercing the Milky Way: an all-sky view of the Orphan Stream
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DOI：
10.1093/mnras/stz457
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发表时间：
2018-12
影响因子：
4.8
通讯作者：
Sergey E. Koposov;V. Belokurov;T. Li;C. Mateu;D. Erkal;C. Grillmair;D. Hendel;A. Price-Whelan
中科院分区：
文献类型：
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作者：
Sergey E. Koposov;V. Belokurov;T. Li;C. Mateu;D. Erkal;C. Grillmair;D. Hendel;A. Price-Whelan
我们使用天体测量，宽带测光，和变化信息从数据发布2欧空局的盖亚使命（GDR 2），以确定成员的孤儿流（OS）在整个天空。这条流在天球赤道的上方和下方以及银河系的两个半球都有迹可循，因此它的可见长度增加到210°，相当于150千秒差距的物理范围。利用大量的RR天琴座恒星在OS中，我们提取准确的距离和自行车在整个伸展的潮汐碎片研究。根据GDR2 RR天琴座的描绘，该气流在天空中呈现出两个明显的扭曲形状，并伴随着切向运动的变化。我们用GDR2红巨星和DECam遗产巡天主序星关闭星创建的RR Lyonis地图进行了补充。天空中OS轨迹的行为在所采用的所有三种示踪剂中是一致的。我们检测到一个强大的非零运动在跨流方向的流的相当大的一部分。碎片轨迹和流动速度之间的这种错位在静态重力势中是无法再现的，这表明与大质量扰动物发生了相互作用。
We use astrometry, broad-band photometry, and variability information from the Data Release 2 of ESA’s Gaia mission (GDR2) to identify members of the Orphan Stream (OS) across the whole sky. The stream is traced above and below the celestial equator and in both Galactic hemispheres, thus increasing its visible length to ∼210° equivalent to ∼150 kpc in physical extent. Taking advantage of the large number of RR Lyrae stars in the OS, we extract accurate distances and proper motions across the entire stretch of the tidal debris studied. As delineated by the GDR2 RR Lyrae, the stream exhibits two prominent twists in its shape on the sky which are accompanied by changes in the tangential motion. We complement the RR Lyrae maps with those created using GDR2 Red Giants and the DECam Legacy Survey Main Sequence Turn-Off stars. The behaviour of the OS track on the sky is consistent across all three tracers employed. We detect a strong non-zero motion in the across-stream direction for a substantial portion of the stream. Such a misalignment between the debris track and the streaming velocity cannot be reproduced in a static gravitational potential and signals an interaction with a massive perturber.