The activity cycle of V833 Tau from photometric data for 1899–2009

Abstract

Photoelectric B-band data and calibrated photographic estimates are used to plot a combined light curve of the red dwarf V833 Tau (dK5e) covering 1899–2009. A frequency analysis was applied to the resulting series of yearly mean B magnitudes, yielding possible photospheric activity cycles acting on various timescales. The high-amplitude variations, up to 0.6m(0.8), follow a cycle with a duration of 78.25 yrs. A 18.8-year cycle with an amplitude of 0.39m–0.16m was also detected, and changes of its characteristics for each observing epoch considered. The star becomes redder at epochs of decreased brightness, suggesting that the 18-year cycle is related to spot-formation processes. The existence of the shorter 6.4-year and 2.5-year cycles reported earlier is confirmed.