基金Supported by the National Natural Science Foundation of China(10633010,11173009)the 973 programme (2007CB815405)+3 种基金the Bureau of Education of Guangzhou Municipality(No.11 Sui-Jiao-Ke[2009])Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(GDUPS)(2009)Yangcheng Scholar Funded Scheme(10A027S)the Joint Laboratory for Optical Astronomy of Chinese Academy of Sciences