Department of Astronomy Beijing Normal University Beijing 100875 China;
School of Physics and Astronomy University of Birmingham Edgbaston Birmingham B152TT UK;
Stellar Astrophysics Centre Department of Physics and Astronomy Aarhus University Ny Munkegade 120 DK-8000 Aarhus C Denmark;
Department of Astronomy Beijing Normal University Beijing 100875 China;
School of Space and Environment Beihang University Beijing 100871 China;
Sydney Institute for Astronomy (SIfA) School of Physics University of Sydney NSW 2006 Australia;
Stellar Astrophysics Centre Department of Physics and Astronomy Aarhus University Ny Munkegade 120 DK-8000 Aarhus C Denmark;
National Astronomical Observatories Chinese Academy of Sciences Beijing 100101 China;
Department of Astronomy Beijing Normal University Beijing 100875 China;
Department of Astronomy Beijing Normal University Beijing 100875 China;
National Astronomical Observatories Chinese Academy of Sciences Beijing 100101 China;