SIMBAD references

BVRI photometry and Hα-line spectroscopy of the short-period RS CVn-binary XY UMa are presented. The light curves as a whole as well as the two eclipse minima are asymmetric. The light level after the primary minimum is lower by about 0.04-0.05mag than that after the secondary one. Two cool spots on the primary with sizes 20° and 10°, temperatures 4630 and 4330K at middle latitudes reproduced well the distortion curve in all colours. The observed Hα profile is quite wide and asymmetric at most the phases out of the eclipses. The radial velocity curve is sinusoidal with semiamplitude K₁=120.7±2.9km/s. The corresponding mass function of the system is 0.082M_☉. The phase behaviour of the Hα-profile implies contribution of emission of the chromospheric regions above the photospheric spots.