1. National Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101 , China
2. China School of Physics and Astronomy, China West Normal University , Nanchong 637000 , China
3. Shi Jiazhuang University , Shi Jiazhuang 050035 , China
4. National Solar Observatory , Boulder, CO 80303 , USA
5. China School of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049 , China
6. China Yunnan Observatories, Chinese Academy of Sciences , Kunming 650216 , China