COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                   Number 2146

                                 Konkoly Observatory
                                 Budapest
                                 1982 May 17

                                 HU ISSN 0374-0676


       HD219634 - A MASSIVE NEW ECLIPSING BINARY


    HD 219634 = HR8854 is a known spectroscopic binary (Pub.
D.D.O. 1, 71, 1939) for which an orbital solution has not,
as yet, been published. Extensive spectroscopic observations 
of the star have been made by Hube during the past 8
years using the 1.88m reflector and the Cassegrain spectrograph 
(reciprocal dispersion 15 A mm^-1) at the Dominion
Astrophysical Observatory, Victoria. An orbital solution
based on approximately 80 radial velocities gives a circular
orbit of period 2.3912 days and,of particular relevance to
the following discussion, a mass function of 0.16 Sun. The
large value of the latter led us to suspect that the system
might be eclipsing.
    On August 21, 1980, Lowe observed the star using a
photon-counting photometer equipped with an EMI9502S 
photomultiplier on the 0.5m telescope at the Devon Observatory.
He detected a primary eclipse but relatively poor sky conditions 
and the brevity of the observing session necessitated
confirmatory observations.
    On 6 nights in November 1981, Gulliver obtained differential 
U,B,V photometry using the #3 0.4m telescope and a
photon-counting system equipped with a cooled RCA 1P21 
photomultiplier at the Kitt Peak National Observatory. Portions
of two primary and two secondary eclipses, plus two out-of
eclipse phase intervals were observed. The Kitt Peak data
are presented in Figure 1, where the magnitudes are taken
differentially with respect to HD 220057, and the phases are
measured from the time of nodal passage, T_0 = JD 2443334.945.
    We note that there are significant night-to-night variations 
in the light curves. In particular, the two sets of
data obtained during primary eclipses are displaced relative
to one another by approximately 0.02m in V and 0.01m in B. We
believe that this represents an intrinsic variation in HD
219634 itself, but we cannot at this time completely rule
out the possibility that it is due in part to a variable
comparison star - HD 220057 has a spectral type B2IV and is,
therefore, in or close to the beta Cephei instability region.

                     [FIGURE 1]

    We classify HD219634 as B0Vn in agreement with Cowley
(1972). The HD spectral type is B8. The difference in
classification is due to the very strong interstellar CaII
K-line. The interstellar reddening amounts to approximately
0.53m in (B-V).

    The secondary component has not been detected 
spectroscopically. The B0Vn primary should have a mass of 
approximately 17 Sun (Allen, 1972). Adopting i ~ 90d and F(M) = 0.16
we find a secondary mass of approximately 4 Sun which, for a
normal dwarf, corresponds to a spectral type of approximately
B8.
    Finally, we note that HD219634 lies on the edge of the
error box of the as-yet-unidentified X-ray source 4U2316+61
(Forman et al, 1978). The available spectroscopic and 
photometric data are suggestive of a strong interaction, including
tidal distortions and mass exchange, between the two components 
and, perhaps, a possible source of X-radiation.
    Details of the spectroscopic and photometric observations 
will be published elsewhere.





                        AUSTIN F. GULLIVER a)
                        DOUGLAS P. HUBE    b)
                        ANDREW LOWE


                        Department of Physics
                        University of Alberta
                        Edmonton, Alberta, Canada


a) Guest Observer, Kitt Peak National Observatory operated
   by the Association of Universities for Research in
   Astronomy under contract with the National Science
   Foundation.

b) Guest Observer, Dominion Astrophysical Observatory,
   National Research Council of Canada.





References:
Allen, C.W.: 1972, Astrophysical Quantities (The
           Athlone Press, London).
Cowley, A.P.: 1972, Astron. J. 77, 750. [BIBCODE 1972AJ.....77..750C ]
Forman, W., Jones, C., Cominsky, L., Julien, P.,
           Murray, S., Peters, G., Tananbaum, H. and Giacconi, R.:
           1978, Astrophys. J. Suppl. 38, 357. [BIBCODE 1978ApJS...38..357F ]