1. Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany
2. Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
3. Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Canberra, ACT 2611, Australia
4. Department of Physics, Western Michigan University, Kalamazoo, MI 49008, USA
5. Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
6. Institute for Solar Physics, Department of Astronomy, Stockholm University, Albanova University Center, SE-106 91 Stockholm, Sweden
7. Institute for Theoretical Astrophysics, University of Oslo, PO Box 1029, Blindern, N-0315 Oslo, Norway