1. Yunnan Observatories, Chinese Academy of Sciences, P.O. Box 110, 650216 Kunming, China
2. Key Laboratory of the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, P. O. Box 110, 650216 Kunming, China
3. Center for Astronomical Mega-Science, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing, 100012, China
4. University of the Chinese Academy of Sciences, Yuquan Road 19#, Shijingshan Block, 100049 Beijing, China