Amplitude Variations in Pulsating Red Supergiants

摘要

We have used long-term AAVSO visual observations and Fourier and waveletanalysis to identify periods and study long-term amplitude variations in 44 redsupergiants. Of these, 12 stars had data which were too sparse and/or had lowamplitude and/or were without conspicuous peaks in the Fourier spectrum; 6stars had only long (2500-4000 days) periods without significant amplitudevariation. The other 26 stars had one or two periods, either "short" (hundredsof days) or "long" (thousands of days), whose amplitudes varied by up to afactor of 8, but more typically 2-4. The median timescale of the amplitudevariation was 18 periods. We interpret the shorter periods as due to pulsation,and the longer periods as analogous to the "long secondary periods" found inpulsating red giants.