The Large Sky Area Multi-Object Fiber Spectroscopic Telescope

Abstract

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) adopts an innovative active optics technique that changes mirror surface continuously to achieve a series different reflecting Schmidt systems at different moments. The key technical innovations makes it a unique astronomical instrument combining the largest aperture with a wide field of view, and it is the telescope with the highest spectrum acquiring rate by 4000 fibers in the world. The observed declination of the telescope covers from - 10° to 90°. There are two major components of the LAMOST survey: The LAMOST ExtraGAlactic Survey (LEGAS) and the LAMOST Experiment for Galactic Understanding and Exploration (LEGUE). It is known that the Milky Way is the only galaxy that we can study in enough detail, and the LEGUE survey can be divided into three parts according to sky coverage: the Galactic spheroid, the disk and the Galactic anticenter, and will observe a huge sample of stars of our Galaxy. At the moment, LAMOST survey focuses on the stellar spectra of our Galaxy, and will obtain optical spectra for statistically complete samples totaling at least 7.5 million Galactic stars from the thin- and thick-disk and halo during the first five year survey. It will open up new windows in near-field cosmology. LAMOST opened a new road to the large scale optical fiber spectroscopic sky surveys in China. As a national large scientific project, the spectra from the survey are opened to all Chinese astronomers. With this huge spectra database stellar kinematics can be obtained and the metallicity distribution function in the Galaxy will be derived, especially those within a few kpc of the Sun. With the structures revealed from such a large survey, it is possible for us to systematically map out the spatial density, Galactocentric rotation velocity and velocity ellipsoid, and chemical abundance of stars as a function of position in the Galaxy. These results will provide important constraints on the present models of Galactic structure, formation history, kinematical and dynamical evolution, chemical evolution, and the distribution of dark matter in the Milky Way. The survey will also provide important clues to the structure of the Galaxy’s gravitational potential, and can pin down the mysterious of the possible structure and sub-structure of dark matter. Based on these results we can test models of dark matter, gravitational collapse, hydrodynamics of gas, stellar formation and feedback including properties of the first generation of stars and enrichment of interstellar medium through supernova explosions.