Affiliation: | (1) Beijing Astronomical Observatory, Chinese Academy of Sciences, 20 Datun Road, Chaoyang, 100012 Beijing, Peoples Republic of China;(2) Institute of Theoretical Astrophysics, University of Oslo, P.O.Box 1029, Blindern, N-0315 Oslo, Norway;(3) Observatoire de Paris, 5, Place Jules Janssen, F-92195 Meudon Cedex, France |