COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2016

                                   Konkoly Observatory
                                   Budapest
                                   1981 September 9

                                   HU ISSN 0374-0676




    THE PERIOD OF THE SYMBIOTIC STAR AG PEGASI




AG Pegasi (WN6 + M3 III) is a well-known symbiotic star. From
spectroscopical observations various authors derived periods
ranging from 790 to 840 days (Merrill 1959, Boyarchuk 1967,
Cowley and Stencel 1973, Hutchings et al. 1975).
The star shows also periodic brightness variations with an
amplitude of about 0.35 mag. in V (Belyakina 1968). The variations 
are probably caused by binary motion of a hot spot on the
M-star (Hutchings et al. 1975). According to those authors
"the light curve may ultimately give us the best value of the
period, since the velocity data are plagued with numerous
difficulties already described".
Between 1973 and 1979 I observed AG Peg photoelectrically in
U, B, V with the 60 cm-reflector II of Sonneberg Observatory.
Photoelectric observations were published by Belyakina 1968,
Mendoza 1972, Fernie 1972, Burchi 1980. Furthermore I observed 
the star on about 1000 Sonneberg sky patrol plates from
1928......1981. On all those observations AG Peg shows periodic
brightness variations best fitted with the following elements:


         Min. - J.D. 242 8250 + 827d. E.


There is a steady decline in mean brightness. From photoelectric 
observations in 1963....1979 I derived a mean value in V
of 0.015 mag. per year.

Further details are given in a forthcoming paper in Mitt.
veranderl. Sterne.





            L. MEINUNGER

            Sonneberg Observatory of
            Central Institute for Astrophysics
            of Academy of Sciences of the GDR





References:

Belyakina, T.S. 1968, A. Zh. 45, 139 [BIBCODE 1968AZh....45..139B ]
Boyarchuk, A.A. 1967, A. Zh. 44, 12 [BIBCODE 1967AZh....44...12B ]
Burchi, R. 1980 IBVS No. 1813
Cowley, A. and R. Stencel 1973, ApJ 184, 687 [BIBCODE 1973ApJ...184..687C ]
Fernie, D.J. 1972, PASP 84, 528 [BIBCODE 1972PASP...84..528F ]
Hutchings, J.B., A.P. Cowley, R.O. Redman 1975, ApJ 201, 404 [BIBCODE 1975ApJ...201..404H ]
Mendoza, E.E. 1972, Bol. Tonantzintla y Tacubaya 6, 211 [BIBCODE 1972BOTT....6..211M ]
Merrill, P.W. 1959, ApJ 129, 44 [BIBCODE 1959ApJ...129...44M ]