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Structure and Evolution of Close Binary Systems
The large light curve changes of XY UMa, observed in the last 20 yr, are interpreted as stellar starspot activity of the primary component of this binary. The 0.4799-day eclipsing binary XY UMa is a unique star as far as its photometric hehaviour is concerned. Shortly after its variability was found by Strohmeier, and its period determined by Kippenhahn (Geyer et al, 1955) I started photoelectric observations, mainly in B and V, of this object and sporadically continued them up to 1975. Eightdoi:10.1007/978-94-010-1483-0_31 fatcat:cjdrokracrep3dp7yhnbrm7j2q