1. Department of Physics and Astronomy, Uppsala University , Box 516, SE-75120 Uppsala , Sweden
2. LUPM-UMR 5299, Université de Montpellier & CNRS , Place Eugene Bataillon, 34095 Montpellier, Cedex 05 , France
3. Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences , Konkoly-Thege Miklós út 15-17, H-1121 Budapest , Hungary
4. Max Planck Institute for Astronomy , Königstuhl 17, D-69117 Heidelberg , Germany
5. Institute of Physics, ELTE Eötvös Loránd University , Pázmány Péter sétány 1/A, H-1117 Budapest , Hungary
6. CSFK, MTA Centre of Excellence , Konkoly-Thege Miklós út 15-17, H-1121 Budapest , Hungary