1. Department of Astronomy, The Ohio State University , 4055 McPherson Laboratory, 140 West 18th Ave., Columbus, OH 43210 , USA
2. Max-Planck-Institut für Astronomie , Königstuhl 17, D-69117 Heidelberg , Germany
3. Leibniz-Institute for Astrophysics Potsdam (AIP) , An der Sternwarte 16, D-14482 Potsdam , Germany
4. Universitäts-Sternwarte, Ludwig-Maximilians-Universität München , Scheinerstrasse 1, D-81679 München , Germany
5. Exzellenzcluster Origins , Boltzmannstraße 2, D-85748 Garching , Germany
6. Institute of Physics & Astronomy, University of Potsdam , Karl-Liebknecht-Str. 24/25, D-14476 Potsdam , Germany
7. INAF – Osservatorio Astrofisico di Catania , via S. Sofia 78, I-95123 Catania , Italy
8. School of Earth and Space Exploration, Arizona State University , 660 S. Mill Ave., Tempe, AZ 85281 , USA
9. Department of Astronomy, University of Science and Technology of China , Hefei 230026 , China