COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2844


                                        Konkoly Observatory
                                        Budapest
                                        6 January 1986

                                        HU ISSN 0374 - 0676



       EVOLUTION OF THE SPECTRA OF THE SYMBIOTIC STAR Z And


   All the spectra were recorded using a D spectrograph mounted on the T 80
cm of the O.H.P. (1979-1982) giving a dispersion of 93 A/mm at Hgamma. The 
wavelength region of interest was lambda 3700 to lambda 5000 A and heated Kodak IIaO
plates were used.

   The emission spectrum is very rich: the following lines were observed,
their intensities varying with time during which they were observed.
   He II lambda 4686 A was always present;
   He I lines were weak in 1979 (September) and in 1982 (January);
   [O III] lambda 4363 A was absent during these periods;
   Fe II, [Fe II], [Fe VII] were seen when He II lambda 4686 was very strong like-
      wise NIII lambda 4640 A.
  TiO bands (alpha system) were very weak in July 1981 and in October 1982.
   In October 1982, the predominant feature of the spectrum was a band
having a wide range of ionization energy.
  We also note the absence of [OIII] 5007 A in all spectra, implying that
there was no development of a nebulosity.
  Measurements in UBV were carried out by other authors: Taranova and Yudin
(1981), Martel and Gravina (1985), and Belyakina (1985). These data can be
interpreted that the star shows oscillations of varying amplitude caused by
explosions of the hot star.
  The oscillations are damping and occur with a period of roughly 700 days.
Colour index measurements suggest that the cold star might be an M6 type
giant, and the hot star might be enveloped in He I, explaining the 
transformation of UV light to visible frequencies.
  We were not able to discover any level of linear polarization which leads
us suppose that there is no favoured direction for the ejection of matter.




                          R. GRAVINA

                     Observatoire de Lyon
                     F-69230 Saint-Genis-Laval, France



References:

Belyakina, I.S., 1985, Inf. Bull. Var. Stars, No. 2698.
Martel, M.T., and Gravina, R., 1985, Inf. Bull. Var. Stars, No. 2750.
Taranova, O.G., and Yudin, B.F., 1981, Astron. Zhu., 58, 1051. [BIBCODE 1981AZh....58.1051T ]