COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1563

                                 Konkoly Observatory
                                 Budapest
                                 1979 March 6




      ON THE RELATION (lg E_pi)/(lg P) FOR STARS OF DIFFERENT
                 TYPES OF VARIABILITY


   As has already been shown (A.Circ. No. 924, 1976) we have
made an attempt of finding dependence in RR Lyrae-type stars 
between long-periodic fluctuations of O-C-(pi) residuals and the
period of light variation (P). Later on the work has been extended 
to a greater number of stars of RR Lyrae-type (80) as well
as to the stars of other types of variability.
    In the figure a very interesting relation between lg E_pi
and lg P (where E_pi is the period pi of a longperiodic fluctuation 
of O-C residuals expressed in E) is illustrated. For eclipsing 
stars P is the period and E is the number of minimum, 
respectively.
    Notations used in the figure are as follows:
           o - stars of RR Lyrae-type
           .  - cepheids
           +  - eclipsing stars
(triangle) - Mira-type stars
    In our work we have referred to the following data on 
investigation of variability in periods of variable stars:
    1.) eclipsing stars - J.M. Kreiner, A.A., Vol. 21, No. 3, 1971
    2.) cepheids P.P. Parenago, Per.Zvezdy 11, 4, 1956
      O.P. Vasilyanovskaya, G.E. Yerlexova, Bull.In-ta astrofiziki,
      AN Tadzh.SSR No. 54, 1970
    3.) Mira-type stars - A.G. Nudzhenko, Per.Zvezdy 19, No. 4, 1974



                             B.N. FIRMANYUK
                        Odessa Astronomical Observatory


                    [FIGURE 1]