Subfeatures < 0.5% of continuum were detected moving through the line profiles of the Be/shell star y Cas over a nine-month period in 1983. While the average spacing and acceleration of the subfeatures is consistent with nonradial pulsation of |m| = 12 +/- 4, large variations in the acceleration of the subfeatures are sometimes seen and some subfeatures appear and disappear suddenly. The subfeatures appeared particularly chaotic on 1983 October 26, five days prior to detection of a strong X-ray flare with the Tenma satellite. The observed period of the subfeature oscillations varies between 7000 and 10,000 seconds which is similar to the transient 6000-second variation in X-ray flux found by EXOSAT in December 1984. No rapid E/C variation is observed in the Hy and He I _5876 emission-line profiles (Refer to PDF file for exact formulas).
Department, Program, or Center
Chester F. Carlson Center for Imaging Science (COS)
Publications of the Astronomical Society of the Pacific 100N624 (1988) 233-242
RIT – Main Campus