A ten-year `active' episode of mass outflow from the Be-star 59 Cyg: facts and implications

A study of the activity surrounding a 10 yr episode of increased mass-outflow for the Be star 59 Cyg identifies long-term patterns of coordinated variability, found in the visual and far UV. In the context of century-long visual studies of the similar long-term variability patterns of 59 Cyg and gamma Cas, two alternative interpretations of such observations as to the significance of Be stars for general stellar structure and evolution are possible: the variability suggests a nonthermal structure for the stellar interior, so that neither mass-loss or luminosity are time-constant; or Be stars do not exist in a long-lasting evolutionary stage, but represent a transition-phase between two such long-term evolutionary stages. The alternatives are not mutually exclusive.