1School of Physics and Technology, Wuhan University, Wuhan, 430072 China
2School of Science, Wuhan University of Technology, Wuhan, 430070 China
3Department of Physics and Mechanical and Electrical Engineering, Hubei University of Education, Wuhan, 430205 China
4Department of Astronomy, Beijing Normal University, Beijing, 100875 China
5Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 USA
6Department of Astrophysics and Cosmology, Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland
© The Author(s) 2017
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