COMMISSION 27 OF THE I.A.U.
              INFORMATION BULLETIN ON VARIABLE STARS
                           Number 2941

                                                 Konkoly Observatory
                                                 Budapest
                                                 7 October 1986

                                                 HU ISSN 0374 - 0676


                 UBV OBSERVATIONS OF R ARAE

Kondo et. al, (1984) and McCluskey and Kondo (1983, 1984)
have drawn attention to peculiarities of the relatively
bright (~7th magnitude) eclipsing binary R Arae
(HD 149730 = HJ 4866), generally on the basis of satellite 
observations which suggest irregular high energy
processes, possibly connected to "mass transfer" events.
   Peculiarities are, in fact, hinted at by the ostensible
photometric characteristics of the system: though
originally designated an Algol type (Roberts, 1894),
Gaposchkin's (1953) light curve clearly shows a rounded
out-of-eclipse variation, which is more in keeping with a
Beta Lyrae type light curve. The system's 4.4 day period
also gives an indication of possible interaction effects,
when seen in context of a Beta Lyrae type light curve
(Paczynski, 1971), (although we should remark that the
notion of a standard Beta Lyrae type variation may well be an
oversimplification for R Arae).
   In this present note, we report a primary minimum of the
variable, which was observed using the Ruth Crisp 41-cm
telescope, at Carter Observatory's Black Birch outstation
(near Blenheim, New Zealand). The minimum was followed
using the three colour U, B, V photometric system (see
e.g., Budding 1985). The main comparison star was
HD 147977, which was checked regularly against HD 150745.
A time of minimum was calculated for each colour using the
"folding paper method". An estimate of the error in time
was obtained from a standard statistical procedure on the
various measurements. The time of minimum thus obtained
was:

       Primary minimum at HJD 2446585.161 +- 0.001


                         [FIGURE 1]


   More time of minimum observations are urged for this
binary. Apart from the evidence such data might have to
bear on the mass transfer process, as discussed by Kondo et
al., (op.cit.) and McCluskey and Kondo (op.cit), there is, more
simply, a need to clarify the value of the period. The
following values have been either deduced, quoted or used
in past literature:

Roberts            (1894, 1901)   deduced     P=4d.42509        :
Hertzsprung        (1942)         deduced     P=4d.42507+0.00003:
Payne-Gaposchkin   (1945)         quoted (?)  P=4d.42509        :
Gaposchkin         (1953)         deduced     P=4d.425115       :
Sahade             (1952)         used        P=4d.42509        :
McCluskey and
Kondo              (1983, 1984)   used        P=4d.92509        :


   Thus, if Hertzsprung's or Gaposchkin's periods represent
improved values, on the basis of more observations, it seems
odd that later workers have not bothered with them; although
Hertzsprung's value has been quoted by Sahade (1952) and
McCluskey and Kondo (op.cit).
   In this present work the value quoted by Payne-Gaposchkin
has been used for the calculation of phases. From figure
(1) we can see that the minimum is appreciably displaced
from phase = 1.00. If we use the epoch of Payne-Gaposchkin,
as quoted by McCluskey and Kondo (1983) we may derive a
mean period, over the last fifty years or so, of 4d.425132,
bearing out the suggestion of an increase given by Gaposchkin
(1953) and noticeably greater than the period used as representative 
for the first fifty years after discovery. Unfortunately 
though, there appears to be too little data on times
of minimum to enable a thorough study of O-C history of the
binary hitherto.


                       KATHRYN M. NIELD
                        JOHN PRIESTLEY
                        EDWIN BUDDING
                   Carter Observatory, PO Box 2909
                       Wellington, New Zealand



References:

Budding, E: 1985, IBVS No. 2779
Gaposchkin, S: 1953, Harvard Annals. 113, No. 2  [BIBCODE 1953AnHar.113...67G ]
Hertzsprung: 1942, B.Z.N., 9, 277 [BIBCODE 1942BAN.....9..275H ]
Kondo, Y, McCluskey, G E, Parsons, S B: 1984, Astrophys. Space Sci. 99, 281 [BIBCODE 1984Ap&SS..99..281K ]
McCluskey, G E, Kondo Y: 1983, Astrophys. J., 266, 755 [BIBCODE 1983ApJ...266..755M ]
McCluskey, G E, Kondo Y: 1984, Publ Astron. Soc. Pacific. 96, 817 [BIBCODE 1984PASP...96..817M ]
Payne-Gaposchkin, C: 1945, Harvard Annals. 115, 46 
Paczynski, B: 1971, Ann. Rev. Astron. Astrophys., 9, 183 [BIBCODE 1971ARA&A...9..183P ]
Roberts, A W: 1894, Astron. J., 124, No., 15. 
Sahade, J: 1952, Astrophys. J., 116, 27 [BIBCODE 1952ApJ...116...27S ]