Accretion Events in Binary Systems: AZ Cas and VV Cep
  The sudden lengthening of orbital period of VV Cep eclipsing binary by about 1% was observed in the last epoch. The mass transfer and/or mass loss are most possible explanations of this event. The photometric behaviour of AZ Cas, the cousin of VV Cep, suggests that the accretion can occur and could be important in this system, too. 
C. Ga{\l}an, M. Miko{\l}ajewski, T. Tomov, M. Wi\c{e}cek, A. Majcher,   P. Wychudzki, E. \'Swierczy\'nski, D. Kolev, T. Bro\...
astro-ph.SR