Photometric Activity of CQ Tau over a Time Interval of 125 Years

The star CQ Tau belongs to the family of UX Ori type stars and is characterized by very complicated photometric behavior and a complex structure of its circumstellar environment. Based on published photometric data, in this article we construct a light curve for this star covering 125 years. It implies that besides a random component characteristic of UX Ori type stars, the changes in brightness also include a large amplitude periodic component with a period of 10 years. It existence was suspected previously and new observations confirm its reality. This indicates the existence of a second component in the neighborhood of the star. Matter flows and density waves caused by the motion of the companion lead to periodic changes in the circumstellar extinction and brightness of the star. This result is discussed in the context of recent observations of CQ Tau with high angular resolution.