星系是宇宙的基本结构单元。阐释星系的集成历史，理解星系形态、结构和性质的规律性和多样性，是二十一世纪天体物理学的重大问题。银河系是唯一能将其星族组成解析为单体，获取其在三维空间、三维速度以及化学元素丰度等多维相空间中的分布，研究其结构及化学动力学性质随时间的演化的盘星系，对阐释星系形成和演化具有重要的意义。

Galaxies are building blocks of cosmic structures. Understanding their assembly history and the mechanism underlying the multiple morphological structures and physical properties is one of the challenges in the 21st century. The Milky Way galaxy is uniquely important in galaxy studies. It is the only one that we can resolve its individual stars and perform detailed studies about the 3D spatial and velocity distributions, stellar ages and chemical compositions.

国家重大科学装置LAMOST（郭守敬望远镜）的建成为系统开展大规模银河系光谱巡天提供了重大机遇。LAMOST银河系光谱巡天一期（2012-2017）已获得了近一千万条高质量光谱，形成了当前世界上最大的的恒星光谱数据库。作为LAMOST银河系光谱巡天的重要组成部分，本团组领导设计、实施了LAMOST反银心方向光谱巡天（LSS-GAC），获得了国际上首个天区覆盖连续、统计无偏的百万量级银河系恒星光谱数据库。

Being a major scientific facility developed in China, LAMOST (also named the Guoshoujing Telescope) has 4000 fibers that have made it possible to conduct systematically spectroscopic survey for the Milky Way. In the period of LAMOST Phase-I (2012-2017) Regular Galactic Surveys, near ten million high quality spectra have been taken, which is currently the largest spectral database in the world. Among others, the LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC) was initiated and designed by our group. At present, we have obtained a statistically complete sample of few million stars distributed in a significant volume of our Galaxy in a contiguous sky area.

本团组进一步利用自己发展的方法，开发了一套适合LAMOST银河系光谱巡天的大气参数（Teff、 log g、[Fe/H]、[alpha/Fe]和[C/Fe]）、视向速度(Vr)的自动测量流水线LSP3，并将获得的参数与其它星表数据相结合（如Gaia），构建包含恒星多维度相空间（三维位置、三维速度、元素丰度、消光、年龄）信息的增值星表。基于增值星表，本团组开展了一系列围绕银盘结构、星族组成及其化学运动学性质和演化、银河系引力势和物质分布（包括暗物质）的前沿研究，为理解和阐释银河系（及一般星系）的形成和演化提供了新的细致可靠的观测依据和约束条件。此外，基于LAMOST获取的海量光谱，我们还发现和证认了一批具有特殊研究价值的稀有天体。

We have developed an automatic parameter determination pipeline, LSP3, to derive stellar atmospheric parameters and line-of-sight velocities. Together with external datasets, such as Gaia, we have constructed value-added star catalogs containing 3D spatial positions and velocities, chemical compositions, interstellar extinctions and stellar ages. Based on our unique value-added catalogs, we have carried out a series of frontier studies on structures, stellar populations, chemical compositions, kinematics of the Galactic disk. We have explored in detail the gravitational potential and matter distribution, including the dark matter, of the Milky Way. Our studies have made significant contributions to enhance the understanding of the assembly of the Milky Way and other galaxies. In addition, with the huge amount of spectra taken by LAMOST, we have successfully discovered a number of rare and highly interesting objects, such as hypervelocity stars.

                            

代表性论文(Selected publications):

• Liu, X.-W.; Yuan, H.-B.; Huo, Z.-Y.; Deng, L.-C.; Hou, J.-L.; Zhao, Y.-H.; Zhao, G.; Shi, J.-R.; Luo, A.-L.; Xiang, M.-S.; Zhang, H.-H.; Huang, Y.; Zhang, H.-W., "LSS-GAC - A LAMOST Spectroscopic Survey of the Galactic Anti-center", 2014, Setting the scene for Gaia and LAMOST, Proc. IAU Symp. 298, Cambridge Univ. Press, p. 310.

• Yuan, H.-B.; Liu, X.-W.; Huo, Z.-Y.; Xiang, M.-S.; Huang, Y.; Chen, B.-Q.; Zhang, H.-H.; Sun, N.-C.;Wang, C.; Zhang, H.-W.; Zhao, Y.-H.; Luo, A.-L.; Shi, J.-R.; Li, G.-P.; Yuan, H.-L.; Dong, Y.-Q.; Li, G.-W.; Hou, Y.-H.; Zhang, Y., "LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC): target selection and the first release of value-added catalogues", 2015, MNRAS, 448, 855.

• Xiang, M.-S.; Liu, X.-W.; Yuan, H.-B.; Huang, Y.; Huo, Z.-Y.; Zhang, H.-W.; Chen, B.-Q.; Zhang, H.-H.; Sun, N.-C.; Wang, C.; Zhao, Y.-H.; Shi, J.-R.; Luo, A.-L.; Li, G.-P.; Wu, Y.; Bai, Z.-R.; Zhang, Y.; Hou, Y.-H.; Yuan, H.-L.; Li, G.-W.; Wei, Z., "The LAMOST stellar parameter pipeline at Peking University - LSP3", 2015, MNRAS, 448, 822.

• Xiang, M.-S.; Liu, X.-W.; Shi, J.-R.; Yuan, H.-B.; Huang, Y.; Chen, B.-Q.; Wang, C.; Tian, Z.-J.; Wu, Y.-Q.; Yang, Y.; Zhang, H.-W.; Huo, Z.-Y.; Ren, J.-J., "The Ages and Masses of a Million Galactic-disk Main-sequence Turnoff and Subgiant Stars from the LAMOST Galactic Spectroscopic Surveys", 2017, ApJS, 232, 2.

• Rebassa-Mansergas, A.; Liu, X.-W.; Cojocaru, R.; Yuan, H.-B.; Torres, S.; García-Berro, E.; Xiang, M.-X.; Huang, Y.; Koester, D.; Hou, Y.-H.; Li, G.; Zhang, Y., "DA white dwarfs from the LSS-GAC survey DR1: the preliminary luminosity and mass functions and formation rate", 2015, MNRAS, 450, 743.

• Xiang, M.-S; Liu, X.-W.; Yuan, H.-B.; Huang, Y.; Wang, C.; Ren, J.-J.; Chen, B.-Q.; Sun, N.-C.; Zhang, H.-W.; Huo, Z.-Y.; Rebassa-Mansergas, A., "The evolution of stellar metallicity gradients of the Milky Way disk from LSS-GAC main sequence turn-off stars: a two-phase disk formation history?", 2015, RAA, 15, 1209.

• Huang, Y.; Liu, X.-W.; Zhang, H.-W.; Yuan, H.-B.; Xiang, M.-S.; Chen, B.-Q.; Ren, J.-J.; Sun, N.-C.;Wang, C.; Zhang, Y.; Hou, Y.-H.; Wang, Y.-F.; Yang, M., "On the metallicity gradients of the Galactic disk as revealed by LSS-GAC red clump stars", 2015, RAA, 15, 1240.

• Chen, B.-Q.; Liu, X.-W.; Yuan, H.-B.; Robin, A.-C.; Huang, Y.; Xiang, M.-S.; Wang, C.; Ren, J.-J.; Tian, Z.-J.; Zhang, H.-W., "Constraining the Galactic structure parameters with the XSTPS-GAC and SDSS photometric surveys", 2017, MNRAS, 464, 2545.

• Huang, Y.; Liu, X.-W.; Yuan, H.-B.; Xiang, M.-S.; Zhang, H.-W.; Chen, B.-Q.; Ren, J.-J.; Wang, C.; Zhang, Y.; Hou, Y.-H.; Wang, Y.-F.; Cao, Z.-H., "The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution", 2016, MNRAS, 463, 2623.

• Huang, Y.; Liu, X.-W.; Zhang, H.-W.; Chen, B.-Q.; Xiang, M.-S.; Wang, C.; Yuan, H.-B.; Tian, Z.-J.; Li, Y.-B.; Wang, B., "Discovery of Two New Hypervelocity Stars from the LAMOST Spectroscopic Surveys", 2017, ApJL, 847, 9.