Abstract
ABSTRACT FF And (sp. dM1e), a BY Dra variable and flare star, is shown to be a double-line spectroscopic binary of period 2d,17 The masses of the components are nearly , and both stars show variation in the intensity of the Balmer and Ca ii H and K emission lines, The system is very similar to YY Gem, though no eclipses have been seen. Using reasonable values for the orbital inclination, we formulate a model for the size and location of the active region observed photometrically on FF And in 1967. Differing photometric periods in 1967 and 1971 may indicate the presence of differential rotation in the system. Key words: variable stars - BY Draconis variables - spectroscopic binaries
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