本项目主要有两个研究内容：1）利用太阳邻域大样本K矮星的运动学和动力学性质，运用多种方法测算银盘的局部物质质量密度分布，对现有的测量和计算方法进行测试和改进，从而进一步解决目前太阳邻域暗物质质量密度分布的问题；2）利用北银极的K矮星数据，计算太阳邻域暗物质质量密度的分布情况，并将之与利用南银极数据计算出的结果相比较，以研究银河系的对称性。本项目创新之处有三：1）使用目前最大的完备样本来研究银盘垂直方向上的物质质量分布；2）首次对同一样本用多种计算方法进行测试，以分析出造成"不同方法不同结果"这一现象的原因；3）首次利用北银极的K矮星来对太阳领域的物质质量进行计算，并与南银极数据的计算结果相互比较验证。LAMOST，SDSS DR9的大样本巡天数据以及申请成功的MMT Hectospec的观测为本项目提供了良好数据的条件；申请人前期太阳邻域引力势的相关研究为本项目的工作提供了强有力的保证。

This program contains two studies: 1) improve the measurement of the local dark matter density and investigate the discrepancy of different measurement methods which each make different assumptions, or data complications; 2) compare the measurement based on the data towards the Galactic north pole with the ones estimated from K-dwarfs towards the Galactic south pole to understand the symmetry of Galaxy. The program will utilize volomn complete sample to study the mass distribution in z-direction of total matter. Meanwhile, it will be the first time to test different methods of mass distribution estimation with such a huge and unity data set. In addition, it is also the first time to use K dwarfs towards the Galactic north pole toestimate the mass distribution in the Solar vcinity and compare the results with the one towards the Galactic south pole. With more and more data, e.g., LAMOST SDSS/DR 9, and MMT Hectospec observation, and my experiences of previous Galactic potential studies, it is possible to take this program.