6 Binarity

We examined the literature for the binarity of our objects (Table 6). Out of 14 objects, at least nine belong to double or triple systems. For the remaining five we have negative speckle information for four and in one case there exists an indication that the star might be a spectroscopic binary. Such an indication is however doubtful, since often the sharp shell lines and the broader hydrogen lines reveal a difference of radial velocities, which is taken as an indication of binarity. In summary only one-third are single objects, or, if we refer to the totality of the components present, 5 out of 25, i.e. 20% This proportion is lower than the one we found in our 1988 paper.

  

Table 6: Binarity of our sample

Indications of binarity from Hoffleit & Jaschek (1982). Speckle observations code is given below.
$^\ast$ noted as SB in Bright Stars fourth Hoffleit D. and Jaschek C. (eds.) 1982, Yale Univ. Observ.
(1) McAlister H.A, Mason B.D., Hartkopf W.I., Shara M.M., 1993, AJ 106, 1639
(2) Hartkopf W.I., McAlister H.A., Franz O.G., 1989, AJ 98, 1014
(3) McAlister H.A., Hartkopf W.I., Hutter D.J., Shara M.M., Franz O.G., 1987, AJ 92, 183.