[1] Univ Maria Curie Sklodowska, Inst Phys, Pl Marii Curie Sklodowskiej 5, PL-20031 Lublin, Poland
[2] Karl Franzens Univ Graz, Inst Phys, IGAM, Univ Pl 5, A-8010 Graz, Austria
[3] Ilia State Univ, Sch Nat Sci & Med, Cholokashvili Ave 3-5, GE-0162 Tbilisi, Georgia
[4] Katholieke Univ Leuven, Ctr Math Plasma Astrophys, Dept Math, Celestijnenlaan 200B, B-3001 Leuven, Belgium
[5] Abastumani Astrophys Observ, Mt Kanobili, Abastumani, Georgia