[1] Osserv Astron Capodimonte, I-80131 Naples, Italy
[2] Univ Basel, Inst Astron, CH-4102 Binningen, Switzerland
[3] Univ Naples Federico II, Dipartimento Sci Fis, I-80125 Naples, Italy
[4] Australian Natl Univ, Mt Stromlo & Siding Spring Observ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia
[5] Case Western Reserve Univ, Dept Astron, Cleveland, OH 44106 USA
[6] Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA
[7] Univ Sternwarte Munchen, D-81679 Munich, Germany