BV PHOTOMETRY AND H-ALPHA SPECTROSCOPY OF THE RS CANUM-VENATICORUM BINARY UX ARIETIS

We present differential BV photometry of UX Ari obtained on 76 nights during 1989-94 and H alpha spectroscopy obtained on 14 nights during t he 1990-91 observing season. The migration of the phase of light minim um indicates a life-time longer than 20 years for the starspots locate d at synchronous latitudes and a life-time in the range 2-8 years for those located at faster rotating latitudes. UX Ari is bluer at light m inimum than at light maximum. We interpret this as due to an increase in the fractional contribution in the blue spectral region from the ho tter secondary as the cool active star becomes faint. The amplitude sh ows a modulation with a period around 10-13 years, apparently anticorr elated with the brightness at light minimum. Lower amplitudes occur wh en the spots are more evenly distributed longitudinally rather than wh en the levels of spot activity are less. The mean brightness also vari es, but with a time-scale longer than 20 years. The H alpha emission e quivalent width does not show any significant phase modulation. The me asured H alpha equivalent widths of both components are, most likely, affected by variations in their relative continuum levels as the activ e star varies.