Chromospheric activity in evolved stars: the rotation-activity connection and the binary-single dichotomy

A tabulation of measured values of the Ca II H and K (S) index are transformed to the original Mount Wilson definition of the index. The tabulation includes main-sequence, evolved, single, and tidally coupled (RS CVn) binary stars. The (S) indices are analyzed against Wilson's (1976) IHK intensity estimates, showing that Wilson's estimates are only a two-state indicator. Ca II H and K fluxes are computed and calibrated with published values of rotation periods. It is found that the single and binary stars are consistent with a single relationship between rotation and Ca II excess emission flux.