COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                   Number 2101

                              Konkoly Observatory
                              Budapest
                              1982 March 4

                              HU ISSN 0374-0676





       PHOTOELECTRIC PHOTOMETRY OF THE ECLIPSING
                  BINARY DM PERSEI



  DM Per (BD +55d616 = HD 14871) was discovered as an Algol
type eclipsing binary by Hoffmeister (1943). The first light
elements are also given by Hoffmeister (1944). Kukarkin and Ghiz
(1949) obtained a new value of the period and a first detailed
photoelectric study of the system was made by Colacevich (1950)
who pointed out a strange behavior of the light curve at the
end of primary minimum where the total light of the system remains
nearly constant in between 0.08 and 0.10 phases and then reaches
the maximum value gradually. Colacevich deduced the geometric
elements and also the absolute dimensions of the system combining 
his photometric data with the spectroscopic elements obtained
by Deutsch (1945). Recently, Scaltriti (1976) obtained a 
photoelectric light curve in yellow colour. Scaltriti solved his curve
with the method of Russell-Merrill and gave the new light elements
as,

      Min I Hel = 24 41920.4543 + 2.7277427d.E.
                            +-6         +-8

He also pointed out that the depth of primary minimum is changing 
and there exist some distortions in the light curve.
  This interesting system was observed photoelectrically at
the Ege University Observatory on 18 nights in 1980 and 1981
observational periods, and a total of 741 and 737 individual
points were obtained in blue and yellow colours, respectively.
The observations were made with the 48 cm Cassegrain telescope
equipped with an unrefrigerated EMI 9781 A photomultiplier tube.
BD + 55d590 and BD + 55d587 were used as comparison and check
star, respectively. No evidence for the variability of the
comparison star was found. All the differential observations
(variable minus comparison) were corrected for the differential
extinction using the extinction coefficients for each night.

                        [FIGURE 1]

  The light and colour curves are presented in Figure 1 where
the magnitude differences have been plotted against the phases
calculated with the elements given by Scaltriti (1976). The
observed minima, the depth variability of primary minimum and
a noticeable displacement of mid-secondary had been reported
by the author previously (Sezer, 1980). Now it can be seen
from the light and colour curves that the system is reddening
at the primary minimum while it is bluer at the secondary
minimum which is consistent with the spectral types of the
components (B5 + A6) given in the literature.
  Actually the total light of the system remains nearly
constant at the end of the primary minimum and then it reaches
the maximum around 0.3 phase which confirms the existence of
similar distortions reported in other publications cited above.
In addition to the variations at the depth of primary minimum
the secondary one also varies from night to night. The analysis
is in progress.
                     
  This project is partly supported by the Turkish Scientific
and Technical Research Council.



                CENGIZ SEZER

        Ege University Observatory
        Bornova-Izmir-Turkey





References :
Colacevich A.: 1950, Mem.Soc.Astron.Ital. 21, 275. [BIBCODE 1950MmSAI..21..275C ]
Deutsch, A.J.: 1945, Astrophys.J. 102, 496. [BIBCODE 1945ApJ...102..496D ]
Hoffmeister, C.: 1943, Astron.Nachr. 274, 36. [BIBCODE 1943AN....274...36H ]
Hoffmeister, C.: 1944, Mitt.Veranderl.Sterne. No. 85.
Kukarkin, B.V. and Ghiz, E.K.: 1949, VS Bull. 6, 335
Scaltriti, F.: 1976, Astron.Astrophys.Suppl. 25, 291. [BIBCODE 1976A&AS...25..291S ]
Sezer, C.: 1980, IBVS No. 1899.