1. Departament de Física, Universitat Politècnica de Catalunya, c/Esteve Terrades 5, E-08860 Castelldefels, Spain
2. Institute for Space Studies of Catalonia, c/Gran Capità 2–4, Edif. Nexus 104, E-08034 Barcelona, Spain
3. INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo, Italy
4. Department of Physics, University of Warwick, Coventry CV4 7AL, UK
5. CAS Key Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
6. Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain
7. Depart. de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
8. GRANTECAN, Cuesta de San José s/n, E-38712 Breña Baja, La Palma, Spain
9. Department of Applied Mathematics, University of Colorado, Boulder, CO 80309-0526, USA
10. Institut für Theoretische Physik und Astrophysik, Universitẗ Kiel, D-24098, Kiel, Germany