NationalAstronomicalObservatories;
Chinese Academy of Sciences;
Beijing 100012;
China;
Observatoire Astronomique de Marseille-Provence;
38;
rue Fric Joliot-Curie;
13388 Marseille Cedex 13;
France;
Physics Department and Tsinghua Center for Astrophysics (THCA);
Tsinghua University;
Beijing 100084;
China;
Graduate University of Chinese Academy of Sciences;
Beijing 100049;
China;
Department of Astronomy;
University of California;
Berkeley;
CA 94720-3411;
USA;