[1] Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany
[2] Univ Bern, Ctr Space & Habitabil, Gesell Str 6, CH-3012 Bern, Switzerland
[3] Austrian Acad Sci, Space Res Inst, Schmiedlstr 6, A-8042 Graz, Austria
[4] Univ Amsterdam, Anton Pannekoek Inst Astron, Sci Pk 904, NL-1098 XII Amsterdam, Netherlands
[5] INAF, Osservatorio Astrofis Arcetri, Largo Enrico Fermi 5, I-50125 Florence, Italy
[6] Observ Univ Geneve, 51 Chemin Maillettes, CH-1290 Versoix, Switzerland
[7] Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
[8] Ist Natl Astrofis, Osservatorio Astron Padova, I-35122 Padua, Italy
[9] Univ Padua, Dipartimento Fis & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy
[10] Cornell Univ, Ithaca, NY 14850 USA
[11] Univ Virginia, Charlottesville, VA 22904 USA