1998A&A...329.1075E

The results of the photoelectric and polarimetric observations of detached binary system U Oph made with 50 cm. AZT-14 telescope at Byurakan Observatory in U, B, V, R bands are presented. The intrinsic character of the polarization and its variable behaviour is confirmed. For the first time a strong change in polarization signal has been detected for 30 min. For at least 23 years the polarization mean value has increased. It is suggested that stellar wind mass loss could be responsible for polarization signal behaviour for long timescales whereas its short-term variations may be caused by eruptive mass outflows within the same process due to asynchronous rotation of the components.