COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 1586

                                Konkoly Observatory
                                Budapest
                                1979 April 19




              LIGHT VARIATIONS OF HD 54475


    HD 54475 is an early type star of magnitude V = 5.79 and spectral
type B9 according to the Henry Draper Catalogue. In the Michigan Spectral
Catalogue it has been classified B3V, a spectral type in accordance with the
UBV and Celescope ultraviolet photometry of Deutschman et al. (1976). Heck
and Manfroid (1975) and Heck (1977) have used HD 54475 as a comparison star
for extensive photoelectric uvby photometry of Ap stars. Although at least
54 uvby observations exist so far, HD 54475 has never been suspected of
photometric variability.
   In January 1977, photoelectric UBV photometry of HD 54475 has been carried
out at La Silla, Chile using the Bochum University 61cm telescope. Observations
of HD 54475 relative to HD 55719, HD 54893 and HD 56410 were made on 25 nights
between January 3 and January 31. The reduction procedures employed were those
described by Stift (1978); combination of 3 to 4 observations for each night
leads to an internal precision of 0.002m - 0.003m in B and V.
   HD 55719, a known SrCrEu star, remained constant throughout this period
within the observational errors; very long-term variations on the 0.01m level
appear to be absent, too. HD 54475 on the other hand exhibited low-amplitude
variations in both magnitude and colour, the amplitudes ranging from 0.02m in V
to 0.04m in U. There is no apparent periodicity in a plot of magnitudes versus
Julian Day (Fig. 1); period search programs employing several different
methods all yielded negative results. Light variations on a time scale of
a few hours like those observed by Elst (1979) in some bright southern B-type
stars have to be excluded.

                        [FIGURE 1]

 Figure 1: UBV observations of HD 54475 relative to HD 55719 plotted versus
       J.D. - 2443100.

    As a conclusion we note that HD 54475 does not fit in any of the
well-established classes of variable stars. Whether this star is an irregular
variable or whether it exhibits periodic variations with pronounced beat
phenomena has to be the subject of further investigations.




                          MARTIN STIFT
                        Institut fur Astronomie
                        Turkenschanzstr. 17
                        A-1180 Wien, Austria



References:

Deutschman, W.A., Davis, R.J. and Schild, R.E.: 1976, Astrophys. J. Suppl. 30, 97 [BIBCODE 1976ApJS...30...97D ]
Elst, E.W.: 1979, Inf. Bull. Var. Stars, No. 1562
Heck, A.: 1977, Astron. Astrophys. Suppl. 27, 47 [BIBCODE 1977A&AS...27...47H ]
Heck, A. and Manfroid, J.: 1975, Astron. Astrophys. Suppl. 22, 323 [BIBCODE 1975A&AS...22..323H ]
Stift, M.J.: 1978, Astron. Astrophys. Suppl. 32, 343 [BIBCODE 1978A&AS...32..343S ]