New tidal debris nearby the Sagittarius leading tail from the LAMOST DR2 M giant stars
New tidal debris nearby the Sagittarius leading tail from the LAMOST DR2 M giant stars
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DOI：
10.1088/1674-4527/16/8/125
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发表时间：
2016-04
影响因子：
1.8
通讯作者：
Jing Li;Chao Liu;J. Carlin;J. Zhong;J. Hou;L. Deng;H. Newberg;Yong Zhang;Yong-Hui Hou
中科院分区：
文献类型：
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作者：
Jing Li;Chao Liu;J. Carlin;J. Zhong;J. Hou;L. Deng;H. Newberg;Yong Zhang;Yong-Hui Hou
我们报道了从LAMOST DR2的M巨星中发现的两组新的潮汐碎片，它们位于北银河帽(NGC)的人马座(SGR)潮流附近。M巨星位于天区2 10°<；Λ<；2 90°，距离10-20kpc，[Fe/H]<；−0.75具有明显的双峰速度分布。我们将两个峰值记为VEL−3+83，其中一个峰值位于−3公里的平均速度范围内，S−1相对于观测到的SGR领先尾巴的平均速度为3公里，另一个峰值为VEL+162+26，其平均速度为SΛ1相对于SGR领先尾巴的162公里。尽管VELΛ−3+83的投影−VGSR关系与SGR前尾非常相似，但与SGR前尾相比，Λ距离关系的相反趋势表明，VEL−3+83与模拟的SGR潮流的任何分支具有不同的三维运动方向。因此，我们认为它是一种与SGR流无关的新的潮汐碎屑。类似地，与Chou等人发现的NGC群相同的另一个子结构VEL+162+26也相对于SGR流朝着不同的方向移动，这意味着它可能具有与SGR潮流不同的起源。
We report two new sets of tidal debris nearby the Sagittarius (Sgr) tidal stream in the north Galactic cap (NGC) identified from the M giant stars in LAMOST DR2. The M giant stars located in the sky area of 210° < Λ < 290°, and having a distance of 10-20 kpc and [Fe/H] < −0.75 show clear bimodality in their velocity distribution. We denote the two peaks as Vel−3+83 for the one within a mean velocity of −3 km s−1 with respect to that of the well observed Sgr leading tail at the same Λ and Vel+162+26 for the other one with a mean velocity of 162 km s−1 with respect to the Sgr leading tail. Although the projected Λ −Vgsr relation of Vel−3+83 is very similar to the Sgr leading tail, the opposite trend in the Λ—distance relation as compared to the Sgr leading tail suggests Vel−3+83 has a different 3D direction of motion with any branch of the simulated Sgr tidal stream from Law & Majewski. Therefore, we propose it is new tidal debris not related to the Sgr stream. Similarly, the other substructure Vel+162+26, which is the same one as the NGC group discovered by Chou et al., also moves toward a different direction with respect to the Sgr stream, implying that it may have a different origin than the Sgr tidal stream.