Abstract

Orbital elements derived from our recent material suggests, in confirmation of an earlier result by Luyten and Ebbighausen, that the line of apsides of the system rotates with a period of 133 years. The lines of the primary component display structure at all phases. At the conjunctions, the profiles are very complicated and can be partly accounted for by blending effects The remaining structure is sometimes very striking and shows variations from cycle to cycle The rotational periods of both components are shorter than the orbital periods Although the spectral lines of the two components suggest almost the same spectral type (B2 for the primary and perhaps B3 for the secondary), the luminosities and the masses suggest that the secondary is actually of spectral type B7 or later. It is suggested that we do not observe the lines of a B7 star because the atmosphere of the secondary component mimics that of a B3 star as a result of the effect of the radiation from the primary and the relatively fast rotation of the secondary.