Ultraviolet and optical spectroscopy reveals the effects of theclose-in (2. 3Rₛtar) companion (Siwarha) to the supergiant, Betelgeuse (Alpha Orionis). This companion is believed to be responsible for theLong Secondary Period (LSP) of the star. Optical circumstellarabsorption increases in strength and expands in phase with the companion. In addition, the dynamics of the chromosphere change, as the companionincreases the chromospheric outflow velocity. These characteristicssuggest that the companion produces a gravitationally focussed tailor wake resulting from stellar wind material from the primary. Other supergiants exhibit Long Secondary Periods as well. We presentfirst results from a program withthe TRES spectrograph at the Whipple Observatory in Arizona, to monitorcircumstellar features in 6 red supergiants to assess the ubiquity andto characterise the circumstellar effects of a companion.
Dupree et al. (Tue,) studied this question.