1. INAF, Osservatorio Astronomico di Trieste, I-34131 Trieste, Italy
2. Astrophysics group, Lennard-Jones Laboratories, Keele University, ST5 5BG Staffordshire, UK
3. Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8583, Japan
4. Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan
5. Konkoly Observatory, Konkoly Thege Miklós út 15-17, H-1121 Budapest, Hungary
6. Department of Physics, University of Basel, Klingelbergstr. 82, CH-4056 Basel, Switzerland
7. Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
8. SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, UK
9. INAF, Osservatorio Astronomico d’Abruzzo, I-64100 Teramo, Italy
10. INFN-Sezione di Perugia, I-06123 Perugia, Italy