使用LAMOST和SDSS-V数据探索银盘对银晕的动力学长期影响

在银河系演化过程中，银盘与银晕之间存在长期的相互作用。观测已发现并合矮星系对银盘动力学产生了显著影响，但盘上结构对晕的长期影响还只存在理论工作中，由于观测样本的限制，缺少相关观测研究。目前光谱巡天得到了极大地发展，LAMOST二期巡天正逐步释放包含大批巨星在内的光谱数据。已开始的SDSS-V Milky Way Mapper (MWM)项目将对全天范围银河系内4~5百万恒星进行光谱观测。本项目将首次利用LAMOST和MWM百万级大样本巨星光谱数据对银盘在长期作用中将角动量转移给银晕的现象开展探究。通过刻画由金属丰度区分的不同星族晕星样本的动力学特征及其随空间位置的变化，寻找银盘影响银晕的动力学观测证据。如发现内晕存在转动速度随银心距衰减且不随金属丰度变化，则可基本证实银盘确实存在向银晕的角动量转移现象。这一探索有利于构建一般盘星系恒星晕的完整的长期演化过程，对理解星系的形成和演化意义重大。

During the evolution of the Milky Way, there exists the secular interaction between the disk and the halo. From observation, those merged satellites have significantly affected the disk dynamics, but the influence of the disk (including the bar) to the halo almost only exists in the theoretical research. Because of the limits of the observations, relative research with observational data is still rare. Now the spectroscopic survey has been fast developing. LAMOST has started its Phase II observation, which keeps releasing millions of spectra of different types of sources, including the giant stars. Meanwhile SDSS-V has also been started, which will observe 4 to 5 million stars in the Milky Way Mapper (MWM) project. Using the large sample from LAMOST and MWM, this project will map the velocity distribution of the inner halo versus the space, analysis the orbit distributions of different populations and for the first time study the angular momentum transferring from the disk to the halo during the secular evolution using the observational spectroscopic data. Mapping the distribution of the dynamical information versus space for different populations, which are divided by the metallicity, will help us find out the observational evidence for the effect on the halo from the disk. Once we find that the rotation velocity decreases versus the galactocentric distance without correlation to the metallicity, then the angular momentum transferring during the secular evolution can be proved. The results will help us build the secular evolution process for the stellar halo of the disk galaxies, which is important for understanding the galaxy formation and evolution.