COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3659  

                                                 Konkoly Observatory
                                                 Budapest
                                                 12 September 1991

                                                 HU ISSN 0374 - 0676


      LSS1160 (=CD-44d 4834) : A REDDENED BETA LYRAE SYSTEM


A programme is currently nearing completion et the South African Astronomical
Observatory (SAAO) to obtain photoelectric photometry (uvby beta/VRI/JHK) for
the 'reddened' and 'extremely reddened' stars from the "Luminous Stars in the
Southern Milky Way" Catalogue (Stephenson & Sanduleak 1971). Star LSS1160 was
found to be variable and was subsequently discovered to be in the New Catalogue
of Suspected Variables (NSV4260, Kukarkin et al. 1982). and to be a Bamberg
variable star (BV1200, Strohmeier & Petterson, 1969) although the type of
variability was not known. We have monitored the star in the Johnson UBV
system during 1989-91 and it appears to be a beta Lyrae type eclipsing system.

LSS1160 was observed with two other stars from the same catalogue to serve as
local comparisons; LSS1172 end LSS1184 are near LSS1160 on the sky and are both
reddened OB stars, though not as reddened as LSS1160. All date were reduced to
the E-region system of Cousins (see Menzies et al. 1989) end the mean values for
the comparison stars are given in Table 1. LSS1184 shows larger standard
deviations in V then the fainter star LSS1172 and the difference between the
two seasons 1989-90 and 1990-91 is quite large; it is possibly variable and the
V magnitude values were not used to correct the LSS1160 data.

A dispersion minimisation program was used to find a period 4.2905+-0.0005 day
and the corrected data are shown in Fig. 1, phased with this period. A
provisional ephemeris is:

       HJD (primary min.) = 2447866.096 + 4.2905 E

The continuously variable light curve, relatively long period and the
early-type nature of the stars indicate the system is a beta Lyrae type
eclipsing binary.

    Preliminary Stromgren photometry gives:

(b-y) = 0.855, m_1 = -0.195, c_1 = 0.065, beta = 2.578,

however, there may remain transformation uncertainties in these
figures (particularly in c_1) because of the high interstellar reddening.
Additionally, the H beta index is probably not a reliable indicator of absolute
magnitude because the system is known to show H alpha emission (Munch 1955).
The colours correspond to a spectral type near B0 reddened by E(b-y)=0.95 (A_v
= 4.09) if the stars are main-sequence or giants (Crawford 1978). The H beta
index is consistent with e B0 III star, so given that H beta could be effected
by emission, the stars are unlikely to be more luminous then class III and
could easily be less.

TABLE 1. UBV photometry of comparison stars

                       V        (B-V)    (U-8)     n
LSS1172 1989-90      9.436     0.716   -0.311     25
                   +-0.006   +-0.004  +-0.006(sd)
        1990-91      9.437     0.719   -0.311     28
                     5         7        8
        adopted      9.437     0.717   -0.311

LSS1184 1989-90      7.603     0.743   -0.289     23
                    10         4        6
        1990-91      7.581     0.742   -0.289     29
                    19         7        6
        adopted      var?      0.743   -0.289

Low-dispersion spectroscopy (100 and 210 A/mm) shows week Balmer lines
of hydrogen. HeI is very week, though HeI4026 is present; HeII lines are not
identified. A feature near H4101 might be SiIV4088 and there is some evidence
for CIII/NIII near 4640-50 A. There is no compelling evidence for
emission lines in the region 3400-5200 A but H alpha is very weak in the
210 A/mm spectrogram and is presumably partly filled by emission.
Identification of all features (except those of hydrogen) is uncertain
because of the low dispersion and rotation effects, but the above notes are
consistent with a type ~B0 as suggested by the Strömgren colours.


                                [FIGURE 1]

 Figure 1. UBV photometry for LSS1160 phased according to the ephemeris
           given in the text.


Assuming the primary star to have V=10.3 (see Fig. 1) and a type B0, results
in a distance of ~1 kpc for class V and ~1.7 kpc for class III. The observed
reddening is then roughly consistent with the average found in Fitzgerald's
region 'I' for distances greater then 1 kpc.

A programme of spectroscopy for radial velocity determination and more
photometry is planned for early 1992.


                      D. KILKENNY, F. VAN WYK,
                      F. MARANG and K. SEKIGUCHI
                      S A Astronomical Observatory
                      P O Box 9, Observatory 7935
                      SOUTH AFRICA

References

Crawford, D.L., 1978. Astr. J., 83, 48. [BIBCODE 1978AJ.....83...48C ]
Fitzgerald, M.P., 1968. Astr. J., 73, 983. [BIBCODE 1968AJ.....73..983F ]
Kukarkin, B.V. et el., 1982. New Catalogue of Suspected
    Variable Stars. Moscow.
Menzies, J.W., Cousins, A.W.J., Banfield, R.M. & Laing, J.D.,
    1989. SAAO Circulars 13, 1. [BIBCODE 1989SAAOC..13....1M ]
Munch, L., 1955. Bol. Obs. Tonantzintla y Tacubaya 2, No. 13, 28. [BIBCODE 1955BOTT....2m..28M ]
Stephenson, C.B. & Sanduleak, N., 1971. Publ. Warner & Swasey
    Obs. Vol 1, No. 1. [BIBCODE 1971PW&SO...1a...1S ]
Strohmeier, W. & Patterson, I., 1969. Inf. Bull. Var. Stars, 330.