Ernst Pollmann
Bundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne e.V. (BAV), Germany
Evidence for Harmonic Orbital Modulation in Pleione and Implications for the Circumstellar Disk
Abstract:
We analyze the long-term variability of the binary system Pleione, which exhibits a dominant periodicity of 218 days, interpreted as the periastron passage of a companion. After removal of long-term trends, the time series reveals, in addition to the fundamental period, a significant secondary component at approximately 109 days. We show that this signal is most likely the first harmonic of the orbital period and results from a non-sinusoidal modulation of the observed variability. Phase folding on the orbital period reveals a pronounced asymmetry, suggesting enhanced interactions near periastron. The observed harmonic structure is consistent with a nonlinear response of the circumstellar disk.