COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1859

                                   Konkoly Observatory
                                   Budapest
                                   1980 October 24

                                   HU ISSN 0374-0676



        SURPRISINGLY HIGH OPTICAL POLARIZATION

                  OF mu CEPHEI



    During August and September 1980 at Belgrade Astronomical
Observatory a high degree of linear polarization of mu Cephei in
V spectral region was observed. The preliminary mean values of
polarization parameters, observed on August 7 and 15 as well as
on September 5 and 9, are: P = 3.8% and Theta = 35^o. Deviations of
the individual measurements from the mean values are insignificant. 
As far as we know this is the highest long lasted value of
the mu Cephei polarization percentage, although some highly scattered 
individual measurements reaching 4% (Grigoryan, 1959) have
been published.
   mu Cephei is a star having long series with a great number
of photoelectric observations - photometric and polarimetric
(e.g. Polyakova, 1975 and 1974). There were also several inconclusive 
attempts to explain the origin of the observed polarization.
It is clear, however, that the additional observations of various
kinds, especially during forthcoming decrease of polarization
percentage we can expect, seem necessary. Therefore, besides
Belgrade polarimetric observations that will be carried on, similar 
observations, as well as photometric ones, in various spectral
regions, including infrared, are desirable. Spectral observations,
especially radial velocities, would be useful, too. Even a series
of speckle interferometric measurements can be of interest.




    JELISAVETA ARSENIJEVIC, ALEKSANDAR KUBICELA and
                  ISTVAN VINCE
          Belgrade Astronomical Observatory

References:
Grigoryan, K.A.,1959, Soobshch,Byur.Obs., 27, 55
Polyakova, T.A., 1974,Astrofizika, 10, 53 [BIBCODE 1974Afz....10...53P ]
           1975,Peremenye Zvezdy, 20, 75 [BIBCODE 1975PZ.....20...75P ]