COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1759

                                    Konkoly Observatory
                                    Budapest
                                    1980 March 20


  SPECTROSCOPIC OBSERVATIONS OF CI CYGNI IN 1978 AND 1979


Two low-dispersion spectra (80 Amm^-1) were taken at the Haute-Provence
Observatory on July 21, 1978 and September 17, 1979. The spectrograph was
equipped with a RCA tube and the spectrum was recorded on IIaO plates. The
exposure times were 40 and 60 minutes, respectively.

In the optical range investigated (from lambda 3750 to 5000) the following
emission lines appear on both spectra (Fig. 1):

- HI, (up to H_10)
- HeI, triplet transitions
- HeII, (lambda 4686)
- NIII, (lambda 4097, 4640)
- MgII, (lambda 4481)
- FeII, (lambda 4178, 4233, 4386, 4415, 4582, 4630)
- {FeII} (lambda 4244, 4287)
- {FeIII} (lambda 4655, 4672, 4755)
- {SII} (lambda 4068)
- CIII, (lambda 4267, 4650)
- {OIII} (lambda 4363, 4959, 5007)

and {NeIII} (lambda 3868) which characterize the nebular surrounding shell.
Let us note that the lines of {OIII} are particularly prominent, thus proving a
high electron temperature (1).

                          [FIGURE 1]

On the other hand {FeVII} (lambda 3760), already observed on 1977 spectra,
seems absent, owing to possible stratification effects (2). HeI singlets
transitions are not present in 1979. Emission lines are observed at lambda
4036 and 4059 which remained unidentified.

It is difficult to assign a pure M-type to the cool giant star from the
presence of the TiO absorption bands alone since the absorption line of CaI
(lambda 4227) and emission line of CaII lambda 3933) are absent.

Our present observations indicate that this star is characterized by the mean
excitation lines (I.P.=35-55 eV). The spectra taken on 1978 and 1979 closely
resemble one another and correspond to the previous near-minimum light (3).


R. GRAVINA
Observatoire de Lyon
69230 Saint-Genis-Laval

References:

(1) Gurzadyan, G.A. 1970, Planetary Nebulae, Reidel Publ. Co., Holland [BIBCODE 1970plne.book.....G ]
(2) Colloque vol. 54, p. 101, Liege 1968
(3) Contributi Asiago No. 330 A. Mammano, L. Rosino and S. Yildizdogdu