COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                       Number 2775


                                      Konkoly Observatory
                                      Budapest
                                      12 August 1985

                                      HU ISSN 0374 - 0676

     PHOTOMETRY OF HR 6384 - AN 80 DAY ELLIPSOIDAL BINARY ?


    Ake and Parsons (1985), in I.B.V.S. Number 2686, drew attention to
IUE spectra of the bright southern star HR 6384 which show the characteristics
of a close binary system containing substantial circumstellar gas.
They suggest that in order to have substantial interaction between the
binary components the binary period is probably several hundred days.
HR 6384 is not known as a variable star.


    In Auckland we have made three colour UBV sets of photoelectric
measures on thirteen nights during May - July 1985, as a start to a
continuing programme to monitor light and colour variations of the system
and identify periodic features if they exist.


    The equipment used was the Mark 1 photoelectric system on the Edith
Winstone Blackwell 50cm Cassegrain telescope, which has been described
previously, (Walker and Marino, 1978),


    HR 6438, (V = 5.88, B-V = +1.07, U-B = +0.86), from Hoffleit (1982)
was used as the primary comparison star and the results have been reduced
from these values.    Observations were also made of the seventh magnitude
star 6 arc minutes north of the programme star, and of HR 6442, as a check
of non-variability of the comparison star.    Mean V magnitude, colour, and
standard deviations for the three stars are:

    star               V    S.D.    B-V    S.D.     U-B    S.D.
    HR 6438          6.153 0.026   +1.787 0.010    +1.340 0.010
   star 6 min north  7.016 0.006    0.429 0.006     0.120 0.010
    HR 6442          5.805 0.003    0.978 0.003     0.773 0.014


    The results for HR 6384 are listed in Table I and plotted in

Figure 1.


                          Table I
           Three colour UBV observations of HR 6384

J.D. 2446000+        V       B-V          U-B  comments
      189.9651       6.152 +1.779       +1.334
      191.9546       6.146  1.781        1.347
      205.9227       6.141  1.801        1.348
      211.9071       6.152  1.798        1.343
      218.9015       6.195  1.795        1.341
      225.9161       6.193  1.783        1.323
      233.0030       6.146  1.798        1.345
      242.8638       6.118  1.795        1.332
      243.9270       6.120  1.788        1.358
      245.8010       6.122  1.790        1.347
      252.8869       6.148  1.785        1.336
      258.9429       6.179  1.775        1.345 poor conditions
      265.8754       6.180  1.768        1.322


                            [FIGURE 1]

 Figure 1   UBV Observations of HR 6384 (HD 155341) during the period
 JD 2446189 - 265 using the ephemeris JD 2446142 + 80 days


    The programme star is clearly variable ranging from 6.118 to
6.195 (V) during the observing interval. Maxima and minima appear to
recur at approximately 40 day intervals with the B-V curve being
modulated to the V variations. On the assumption derived from the
IUE spectra that the system is a binary with associated circumstellar
matter, the light and colour curves appear consistent with an
ellipsoidal binary having an orbital period of approximately 80 days.


    Photoelectric photometry is continuing during the current
observing season.





                W.S.G. WALKER, B.F. MARINO and G. HERDMAN
                Auckland Observatory of the Auckland
                Astronomical Society Inc.
                P.O. Box 2640, Auckland, New Zealand,





References:


Ake, T.B., and Parsons, S.B., 1985, I.B.V.S. No 2686.
Walker, W.S.G, and Marino, B.F., 1978, Publ No 6 (C78), V.S. Sect.,
      Roy. Ast. Soc. N. Z.