基于LAMOST和Gaia研究太阳邻域的多星族非对称漂移效应

Asymmetric Drift Effect of Mono-age Populationsin Solar Neighborhood Based on LAMOST and Gaia

基于LAMOST和Gaia巡天数据交叉匹配得到的约16000颗红团簇星和一个简化的动力学模型,对太阳邻域的非对称漂移效应作了统计分析。发现在径向距离R=[7,9]kpc,垂向距离Z=[-0.5,0.5]kpc的非对称漂移速度的平均值约为20.34 km·s^(-1),并且进一步揭示出在这个空间范围内多年龄星族的非对称漂移性质,详细讨论了R-Z、X-Y、l-b和[α/Fe]-[Fe/H]平面上的非对称漂移速度的特征。在R-Z平面上发现太阳位置附近的非对称漂移速度大小为16~22 km·s^(-1),并且随着R的增加,非对称漂移速度逐渐增大,但在Z平面上暂未探测到非对称漂移速度明显的特征。在X-Y平面上恒星的分布也展示出非对称漂移速度随着径向距离向外变化而逐渐增大的特征。在银经银纬平面上,Va在经度为150°~240°时较大,约为22 km·s^(-1)。最后,研究发现年龄为0~6 Gyr的恒星的非对称漂移速度和金属丰度的相关性相对更加明显。

About 16000 red clump stars obtained from LAMOST and Gaia sky survey datum are employed to analyze the asymmetric drift effect of solar neighborhood in the disk by a simplified model.It is found that 20.34 km·s^(-1)is the average asymmetric drift velocity within the radial distance of R=[7,9]kpc and the vertical distance of Z=[-0.5,0.5]kpc.In addition,the asymmetric drift property of mono-age populations in this spacial range is revealed and the characteristics of asymmetric drift velocity on R-Z,X-Y,l-b and[α/Fe]-[Fe/H]planes are discussed in details.On the R-Z plane,the asymmetric drift velocity near the sun is from 16 to 22 km·s^(-1),which will increase gradually with the increase of R.However,the asymmetric drift velocity on the Z plane has shown almost no obvious characteristics.On the X-Y plane,the distribution of stars also reveals the increasing pattern of asymmetric drift velocity following the outward change of R.On the l-b plane,the Va velocity is larger at longitude 150°~240°,which is about 22 km·s^(-1).Finally,it is discovered that the asymmetrical drift velocity of stars belonging to 0~6 Gyr is more strongly correlated with metallicity.