[1] Max Planck Inst Extraterr Phys, D-85748 Garching, Germany
[2] Univ Maryland, Baltimore, MD 21250 USA
[3] Osservatorio Astron Bologna, INAF, I-40127 Bologna, Italy
[4] Univ Toulouse, CNRS, Lab Astrophys Toulouse Tarbes, F-31400 Toulouse, France
[5] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA
[6] Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy
[7] Univ Nacl Autonoma Mexico, Inst Astron, Ensenada, Baja California, Mexico
[8] Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA
[9] ETH, Dept Phys, CH-8093 Zurich, Switzerland
[10] Univ Aix Marseille, Lab Astrophys Marseille, CNRS, F-13388 Marseille 13, France
[11] ESO, D-85748 Garching, Germany
[12] Osserv Astron Padova, INAF, Padua, Italy
[13] Ist Astrofis Spaziale & Fis Cosm Milano, INAF, I-20133 Milan, Italy
[14] Univ Bologna, Dipartimento Astron, I-40127 Bologna, Italy
[15] Osserv Astron Brera, INAF, I-20121 Milan, Italy
[16] Osserv Astrofis Arcetri, I-50125 Florence, Italy
[17] Max Planck Inst Plasma Phys, D-85748 Garching, Germany
[18] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[19] TUM, Excellence Cluster Universe, D-85748 Garching, Germany
[20] CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain
[21] Univ Padua, Dipartimento Astron, I-35122 Padua, Italy
[22] CALTECH, Pasadena, CA 91125 USA
[23] Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA
[24] Ctr Phys Theor, Marseille, France
[25] Univ Paris 06, Inst Astrophys Paris, Paris, France
[26] Osserv Astron Roma, INAF, I-00040 Monte Porzio Catone, Italy