[1] Case Western Reserve Univ, Dept Astron, Cleveland, OH 44106 USA
[2] Youngstown State Univ, Dept Phys & Astron, Youngstown, OH 44555 USA
[3] Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V9E 2E7, Canada
[4] Peking Univ, Dept Astron, Beijing 100871, Peoples R China
[5] Peking Univ, Kavli Inst Astron & Astrophys, Beijing 100871, Peoples R China
[6] Shanghai Jiao Tong Univ, Dept Phys & Astron, Ctr Astron & Astrophys, Shanghai 200240, Peoples R China
[7] Shanghai Jiao Tong Univ, Shanghai Key Lab Particle Phys & Cosmol, Shanghai 200240, Peoples R China
[8] Canada France Hawaii Telescope Corp, Kamuela, HI 96743 USA