BV PHOTOMETRY AND H-ALPHA SPECTROSCOPY OF THE RS CANUM-VENATICORUM BINARY V711 TAURI

Differential BV photometry of V711 Tau obtained on a total of 120 nigh ts during the years 1984-91 and Halpha spectroscopy obtained on 14 nig hts during the 1990-91 observing season are presented. We find that th e mean light level of the system during the period 1975-82 was fainter by approximately 0.05 mag than that during the period 1982-91. The ch ange in the mean light level probably arises from a global reduction i n the area of spots or from the disappearance of spots from the polar region. At larger amplitudes the brightness at minimum decreases and t he brightness at maximum increases, both converging to a particular va lue of DELTAV at very low amplitudes. Phase of light minima observed d uring 1975-91 lie on two independent near-straight lines, implying tha t spots are confined predominantly to two different latitude belts. Th e Halpha equivalent widths did not show any orbital modulation during the period of our observations. The spectra obtained on one night (199 1 Feb. 6) show a sudden drop in equivalent width; this occurs during t he descending branch of the light curve.