[1] Univ Bologna, Dipartimento Astron, I-40127 Bologna, Italy
[2] Osservatorio Astron Bologna, INAF, I-40127 Bologna, Italy
[3] Max Planck Inst Extraterr Phys, D-85748 Garching, Germany
[4] CALTECH, Pasadena, CA 91125 USA
[5] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA
[6] Excellence Cluster Univ, D-85748 Garching, Germany
[7] Univ Arizona, Steward Observ, Tucson, AZ 85721 USA
[8] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[9] Max Planck Inst Astron, D-69117 Heidelberg, Germany
[10] Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA
[11] ETH, Dept Phys, CH-8093 Zurich, Switzerland
[12] ESO, D-85748 Garching, Germany
[13] Osserv Astron Roma, INAF, I-00040 Monte Porzio Catone, Rm, Italy
[14] Univ Aix Marseille, CNRS, OAMP, Lab Astrophys Marseille, F-13388 Marseille 13, France
[15] INAF IASF, I-20133 Milan, Italy
[16] Osserv Astron Brera, INAF, I-20121 Milan, Italy
[17] Univ Toulouse, CNRS, Lab Astrophys Toulouse Tarbes, F-31400 Toulouse, France