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H-alpha photometry of UX ARIETIS during 1979-80

1981; Institute of Physics; Volume: 93; Linguagem: Inglês

10.1086/130865

1538-3873

E. F. Guinan, G. P. McCook, J. L. Fragola, W. C. O'Donnell, Grant Andrew, A.G. Weisenberger,

Solar and Space Plasma Dynamics

The 6.438 d RS CVn-type binary UX Ari was photoelectrically observed on 17 nights from October 1979 to February 1980. Using narrow- and intermediate-band interference filters centered near tne Balmer H-alpha line, the alpha index was formed from data yielding the net H-alpha line strength. The light curve formed from 6585 wavelength intermediate-band data was observed with an amplitude of 0.04 m, and minimum light occurring near the 0.87 phase. The value of the alpha index indicates H-alpha emission at all orbital phases and a study of all available photometry of the system reveals significant changes in the light amplitude, mean light level, and the phase at which minimum light occurs. It is concluded that small light amplitudes are due to star spots located at high stellar latitudes or spread evenly over the stellar surface, and large amplitudes are the result of spots located closer to the equator.