COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 2686

                                   Konkoly Observatory
                                   Budapest
                                   19 March 1985

                                   HU ISSN 0374 - 0676





          HR 6384: A PROBABLE INTERACTING BINARY


  Although little is known about this southern-hemisphere star, recent IUE
spectra obtained by us show the characteristics of a close binary system
containing substantial circumstellar gas. The only known spectral
classification is M1-2 II-III + A (Houk and Cowley 1975). BV photometry
quoted by Hoffleit (1682) gives V= 6.09, B-V= 1.78. No radial velocities are
found in the literature.


 The far-UV spectrum has very complex absorption and possible emission
features. It resembles the spectra at some phases of the known interacting
binaries SX Cas (Plavec, Weiland, and Koch 1982) and HD 207739 (Parsons, Holm,
and Kondo 1883), and partial eclipses in the zeta Aurigae systems such as VV 
Cep (Hagen et al. 1980) and 22 Vul (Ake, Parsons, and Kondo 1884). Figure 1
suggests an embedded or obscured secondary hotter than type A. In order to
have substantial interaction between the components, the period of the binary
is probably hundreds of days.


Ground-based photometric and spectroscopic observations are strongly urged.
HR 6384 is the more southerly of a bright pair separated by B arcmin.  The
nearest comparison stars, designated by 59 and 58 on chart 161 of the  AAVSO
Variable Star Atlas, are HR 6438 (G8 Ib-II, V= 5.88, B-V= 1.07, U-B= 0.86) and
HR 6442 (G8-K0 III, V= 5.80, B-V= 1.00) (data from Hoffleit 1982).
Coordinates for 1985 (derived from SAO Catalog) :


HR 6384 (HD 155341, CPD-56 8098) 17h 12m 57.0s -56d 52' 17"
HR 6438 (HD 156768, CPD-57 8478) 17h 21m 37.3s -57d 59' 47"
HR 6442 (HD 156854, CPD-56 8191) 17h 21m 50.8s -56d 30' 42"

                          [FIGURE 1]

  Fig. 1. IUE SWP spectrum of HR 6384 (bottom) and 22 Vul (top) at partial
  and out-of-eclipse phases. HR 6384 resembles 22 Vul at partial eclipse,
  where the added continuous and line absorption from the outer atmosphere
  of the G3 Ib-II primary strongly distorts the spectrum of the B9 secondary.


                      THOMAS B. AKE and SIDNEY B. PARSONS
                      Computer Sciences Corporation
                      Space Telescope Science Institute
                      Homewood Campus
                      Baltimore, MD 21218. U.S.A.


References:

Ake, T.B., Parsons, S.B., and Kondo, Y. 1984, NASA CP-2349, p. 369. [BIBCODE 1984NASCP2349..369A ]
Hagen, W., Black, J.H., Dupree, A.K., and Holm, A.V. 1980, Astrophys. J.
  238, 203. [BIBCODE 1980ApJ...238..203H ]
Hoffleit, D. 1982, The Bright Star Catalogue, Yale Univ. Obs.
Houk, N., and Cowley, A.P. 1975, University of Michigan Catalogue of
  Two-Dimensional Spectral Types for the HD Stars, Vol. 1. [BIBCODE 1975mcts.book.....H ]
Parsons, S.B., Holm, A.V., and Kondo, Y. 1983, Astrophys. J. (Letters)
  264, L19. [BIBCODE 1983ApJ...264L..19P ]
Plavec, M.J., Weiland, J.L., and Koch, R.H. 1982, Astrophys. J. 256, 206. [BIBCODE 1982ApJ...256..206P ]