Long-term photometry of the Wolf-Rayet stars WR 137, WR 140, WR 148, and WR 153

摘要

In 1991, a long term UBV-photometry campaign of four Wolf-Rayet stars wasstarted using the 60 cm telescope of the National Astronomical ObservatoryRozhen, Bulgaria. Here we report on our observational results and discuss thelight variations. The star WR 137 showed only random light variations, whichare probably due to dynamical wind instabilities but not to eclipses. WR 140featured a dip in the light curve, the amplitude increasing towards shorterwavelengths. The probable cause is electron and Rayleigh scattering when thestar was eclipsed by a dust envelope. In the case of WR 148 we found a periodof 4.3 days and significant scatter in the light curves. Additionally thereseems to be a long term variation with a period of 4 years. Our photometry ofWR 153 is consistent with the quadruple model for this star.