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《天文和天体物理学研究(英文版)》 2011-09
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Kinematics and stellar population properties of the Andromeda galaxy by using the spectroscopic observations of the Guoshoujing Telescope

Hu Zou 1,2,Yan-Bin Yang 1,Tian-Meng Zhang 1,Jun Ma 1,Xu Zhou 1,Ali Luo 1,Hao-Tong Zhang 1,Zhong-Rui Bai 1 and Yong-Heng Zhao 1 1 National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100012,China 2 Graduate University of Chinese Academy of Sciences,Beijing 100049,China  
The Andromeda galaxy was observed by the Guoshoujing Telescope (formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope — LAMOST),during the 2009 commissioning phase.Due to the absence of standard stars for flux calibration,we use the photometric data of 15 intermediate bands in the Beijing-Arizona-Taipei-Connecticut (BATC) survey to calibrate the spectra.In total,59 spectra located in the bulge and disk of the galaxy are obtained.Kinematic and stellar population properties of the stellar content are derived with these spectra.We obtain the global velocity field and calculate corresponding rotation velocities out to about 7 kpc along the major axis.These rotation velocity measurements complement those of the gas content,such as the H I and CO.The radial velocity dispersion shows that the stars in the bulge are more dynamically thermal and the disk is more rotationally-supported.The age distribution shows that the bulge was formed about 12 Gyr ago,the disk is relatively younger and the ages of some regions along the spiral arms can reach as young as about 1 Gyr.These young stellar populations have a relatively richer abundance and larger reddening.The overall average metallicity of the galaxy approximates the solar metallicity and a very weak abundance gradient is gained.The reddening map gives a picture of a dust-free bulge and a distinct dusty ring in the disk.
【Fund】: supported by the National Natural Science Foundation of China (GrantNos. 10873016 10633020 10603006 10803007 10903011 11003021 and 11073032);; by the National Basic Research Program of China (973 Program; Nos. 2007CB815403 2010CB833004 and 2009CB82480X)
【CateGory Index】: P152
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