SPOT evolution on the T Tauri star V 410 Tau

Abstract

UBVRI photometry of V410 Tau has been obtained on about 200 nights between 1981 and 1987. A period of 1.8710 days adequately represents the variation over the entire 5.4 yr span of the present observations. The shape and amplitude of the light curve change from year to year, as expected if spots of changing size, temperature, and distribution pattern are reponsible. One major active region has possibly persisted for over one thousand rotations. An ephemeris for its transit (i.e., time of light minimum) is T(min)=JD 2446861.629 + 1.8710 E. Flares, in U, are seen primarily at times near those of transit. One was partially time resolved, lasting for a few hours. The slopes of the relations between the colors and V have changed only marginally with time, despite a doubling of the amplitude. Two-component models in which the spots have temperatures 1000-1400K below that of the photosphere and cover up to 42 percent of the surface adequately account for the observed amplitude as a function of wavelength. The change in shape and amplitude of the light curve with time can be understood in terms of the presence of a second, smaller, active region, which drifts relative to the first atmore » a rate implying fractional differential rotation of 0.1 percent. 17 references.« less