A new unique phenomenon for the RY Scuti binary star

Abstract

We present the results of reanalysis of old electrophotometric data on RY Scuti obtained at the Abastumani Astrophysical Observatory, Georgia, during 1972–1990 and at the Maidanak Observatory, Uzbekistan, during 1979–1991. Unstable processes in RY Sct from period to period, from month to month and from year to year are revealed. The magnitude of this variation is from hundredths to tenths. Furthermore, periodic changes in the system's light are displayed near the first maximum on timescales of a few years. This is of great interest with regard to some similar variations seen in luminous blue variable stars and, in particular, in S Dor-type stars. This also could be closely related to the question of why RY Sct ejected its nebula.