COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1611

                                   Konkoly Observatory
                                   Budapest
                                   1979 May 28



   DISCOVERY OF A PERIOD IN THE SYMBIOTIC STAR AG DRACONIS



    AG Dra is a well-known symbiotic star. Its photographic
light-curve resembles that of the nova-like stars (Robinson,
1969; Splittgerber, 1974). Since 1955 this star has been in a
quiet phase and has shown only small variations about the 
minimum light.
    Since February 1974 I have observed AG Dra photoelectrically 
in U, B, V with the 60cm-reflektor II of Sonneberg Observatory. 
During this time the star has been slowly variable with
small amplitude in V and B, but with large amplitude in U (see
Fig.1). The same behaviour was observed by Beljakina (1969) in
1965 ....1967. Beljakina (l.c.) concluded from her observations
that the variations were irregular, which, however, is not the
case. The U variations are clearly periodic with the following
elements:
            U_max = J.D. 243 8900 + 554d*E.

There are good reasons for assuming that all symbiotic stars
are binaries containing an evolved red giant and a hot main
sequence or white dwarf companion (Bath, 1977; Allen, 1978). But
so far only three stars of this class could definitively been
shown to be binaries (by T CrB; AR Pav; AG Peg; see Allen 1978),
I think that the observations of AG Dra given in this paper
could well be explained by binary motion of a hot source. But
before a reliable model can be constructed, there are more 
photoelectric and spectroscopic observations necessary.



                               L. MEINUNGER
                           Sonneberg Observatory of
                         Central Institute for Astrophysik
                         of Academy of Sciences of the DDR

References:

Allen, D.A. 1978, Anglo-Australian Obs. No. 12
Bath, G.T. 1977, MN 178, 203 [BIBCODE 1977MNRAS.178..203B ]
Beljakina, T.S. 1969, Iswest.Krim Obs. 40, 39
Robinson, L. 1969, VS 16, 507 [BIBCODE 1969PZ.....16..507R ]
Splittgerber, E., 1974, Mitt. veranderl.Sterne 6, 193 [BIBCODE 1975MitVS...6..193S ]


                       [FIGURE 1]