GD-1星流金属丰度与运动特性分析

星流在星系形成与演化过程中扮演了重要的角色,对银河系中星流的研究将有助于进一步探究银河系的合并历史.将LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope)DR6光谱数据以及SDSS(Sloan Digital Sky Survey)DR12光谱数据分别与Gaia(Global Astrometric Interferometer for Astrophysics)DR2天体测量数据交叉匹配,获得恒星自行等数据.对GD-1星流在速度空间、几何空间和金属丰度上进行限制,从LAMOST DR6和SDSS DR12数据中共获得了157颗星流成员星.GD-1星流的平均金属丰度为Fe/H]=-2.16±0.10 dex,延伸长度超过80°.收集前人给出的GD-1星流高概率成员星,组成较大的成员星样本进行对比分析,发现GD-1星流的金属丰度分布呈现内低外高的特点,沿着星流方向径向速度分布特点是两端大、中间小,?₁=-20°(?₁为GD-1星流坐标系横坐标)和?₁=-60°附近的间隙是因为成员星运动差异形成的.根据成员星分布及其速度分布特性,推测GD-1星流起源位置是在?₁=-40°附近.

Analysis on the Metal Abundance and Motion Property of GD-1 Star Streaming

The star streaming plays an important role in the formation and development of galaxies,and the study of star streaming in the Milky Way will help us further explore the origin and evolution of the Milky Way.The spectrum data of LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope)DR6 and SDSS(Sloan Digital Sky Survey)DR12 were cross-matched with the astrometric data of Gaia(Global Astrometric Interferometer for Astrophysics)DR2,respectively,to obtain the data of proper motion,etc.By limiting the velocity space,geometric space and metal abundance of the GD-1 star streaming,we obtained a total of 157 member stars of the star streaming from LAMOST DR6 and SDSS DR12.The average metal abundance of GD-1 star streaming isFe/H]=-2.16±0.10 dex,the elongation of star streaming is about 80°.The high probability member stars of GD-1 star streaming given by predecessors were collected to form larger member samples for comparative analysis.The metal abundance distribution of the GD-1 star streaming is found to be low inside and high outside,the radial velocity distribution along the star streaming is characterized by large velocities at both ends and small velocities in the middle.The gap between ?1=-20°(?₁ is the horizontal coordinate of the GD-1 star streaming coordinate system)and ?₁=-60° is due to the movement differences of member stars.According to the distribution of member stars and their velocity distribution property,it is speculated that the origin position of GD-1 star streaming is near ?1=-40°.