Variable linear polarization has been detected in CH Cyg. Observations in 1977–79 (UBV) and 1979–80 (UBVRI) are presented. The amount of polarisation increases towards ultraviolet and the observed values range from 0.34 to 1 .85 % in the ultraviolet, and 0.04 to 0.68 % in the yellow light. In the red and infrared observations the polarizationwas typically less than 0.1 %. During the interval September 1977 – February 1978 and in May 1980 a second component of polarization, with different direction and wavelength dependence, was present, resulting in a strong rotation of the position angle as a function of wavelength. The R and I observations of May 1980 (PR ≅ 0.4 %, PI ≅ 0.5%) showed that the second component was increasing towards the infrared. The peculiar wavelength dependence of polarization and position angle could be explained by variations in particle size and scattering geometry in a complicated dust envelope around the M giant. Another hypothesis is that the component of polarization increasing towards the ultraviolet is produced by electron scattering in an extended envelope of a hot companion and the second component by transient dust envelope of the M giant.

Low spectral resolution observations (∼ 6 A) were obtained with the International Ultraviolet Explorer (IUE) during its eclipse phase. Additional data obtained by other IUE groups have been included in our eclipse observations, enabling us to examine the UV spectral properties of this system over nearly an entire orbit that spans early 1979 through mid-1981. Data obtained over this time interval suggest an overall decline in UV emission consistent with the decline of optical emission following the outburst of 1975, where CI Cyg attained an increase of ∼ 3 magnitudes in the visual. The short wavelength spectrum λλ1200-2000 A is characterized by numerous intense high excitation emission lines that become more prominent out of eclipse. The LWR wavelength range λλ2000-3200 A exhibits a few more additional lines of 0 III, Mg II and He II that are superimposed on continuum that rises gradually with increasing wavelength. Additionally, OH emission bands are identified at λλ3064, 2875 A (cf. Diecke and Crosswhite 1962). Collaborative ground-based observations of CI Cyg with W. Blair of McGraw Hill Observatory suggest the presence of the Balmer continuum jump at λ3646 A, and enables us to ascribe the UV continuum observed with IUE to mainly Balmer free-bound recombination emission.

High and low resolution IUE spectra of CI Cyg were obtained at VTLSPA during 1979-81 allowing for an analysis of the spectral variations related to the decreasing activity of the star, and to the eclipse (June 1980).

In the high resolution spectra the emission lines have a width slightly larger than the instrumental one. This fact is particularly evident in the HeII 1640 A line and could be related to the peculiar behaviour of this line at low resolution as reported by Michalitsianos et al. (this volume). A systematic radial velocity difference between permitted and intercombination lines was found; this difference should be connected with the structure of the emitting region(s). “Secular” and eclipse varia tion was found in particular in the intercombination line intensities (Viotti et al. 1980). An electron density of ∼ 0.3–1.5×1010 cm–3 was evaluated from the intensity ratios of the NIII] emission lines. No significant difference in these ratios and in the CIII]/NIII] ratio as well was found,during 1979, 1980 (eclipse) and 1981 suggesting no large Ne variation with both the activity phase and eclipse of the star. This result should imply a low density gradient in the partially eclipsed NIII] and CIII] regions. A more detailed analysis of the high resolution data is in course to better clearfy these points, and their implications on the possible models for CI Cyg.

The observations of CI Cyg were carried out with the Toruń 60/90 cm Schmidt telescope with the objective prism giving a dispersion of 250 A/mm at H-gamma. Intensity traces of 20 selected spectra , made on the Kodak IIa-O plates, were made. The results were corrected for all instrumental effects and the interstellar extinction. The relative emission lines intensities have been obtained from the tracings after normalization to H-beta = 100.

The spectra were typical for the quiet symbiotic star. So, all changes in the spectrum were caused by geometrical effects (eclipse).

En 1971 et 1972, cette étoile présentait un spectre d’émission comorenant des raies de l’hvdrogène et les métaux ionisés Call. Fell, etc… se superposant sur un fond continu sans raie d’absorption, [Fell] est présent par deux raies faibles, les raies de l’hydrogène, de Fell et de CrII présentaient un profil P Cyg.

Le 4 Juillet 1975, Madame Y. Andrillat a sienalé la disparition de la raie de Hel 10830. Nous avons obtenu immediatement un spectre à 20 A mm-1 au télescope de 152 cm. Ce spectre est un spectre d’absorption où seules les raies de l’hydrogène présentent des émissions à structures complexes.

In our paper (Ch. Fehrenbach and C.C. Huang, 1981) we have described the details of our spectroscopic observations of CI Cyg in 1980. In that year, the star showed a fair presence of bright forbidden lines of [FeV ]and very strong emission lines of high and low excitation, including forbidden [0 III ] , [Ne III], [Fe II ] and [S II] and permitted 0 III, N III as well as He I and Fe II … etc … The He II 4686 A was very strong. The Balmer lines were the strongest emission features in the spectrum and Hα and Hβ were double. There were two groups of velocities in 1980, one was positive for forbidden lines and the other was negative for the permitted lines. The displacements of Balmer lines showed a regression.

We report optical emission line variations in CI Cygni during the 1980 eclipse.

The formation of a new planetary nebula should be a rare event, and the case of V1016 Cyg may represent such an example. This is the reason of the considerable interest of the astronomers in this star since the discovery of its outburst in 1965.

Two coudé spectra of V1016 Cyg taken on June 24 and 27, 1979 were reduced, using a computer programme developed in Marseille. Radial velocities and full widths at half maximum were measured for the emission lines, and are summarized in the following table were VR is the mean radial velocity in km s-1, DV the velocity corresponding to the mean FWHM and Xi the effective ionization potential for the ion.

The variable emission-line object V1329 Cyg (= HBV 475) was discover red by Kohoutek (1969).Crampton and Grygar (1969) identified more than 100 emission lines in the blue portion of the spectrum, while Andrillat (1969) found evidence for the late-type (M) spectrum in the near infrared. This justified the classification of the object among the symbiotic stars. The classification was subsequently confirmed by all authors who studied the spectroscopic evolution of the object.

In this paper, I shall present another model for V1329 Cyg. Grygar et al. (1979) proposed a long period eclipsing binary model consisting of a massive M giant and a hot component. Some problems, however, have remained on the binary model. Namely, the mass function is too large, the amplitude of the light variations changes from period to period, the light curve differs from that of Algol type systems and is similar to long period binaries, and so on (Iijima et al. 1981). It has been believed that some peculiarities in the system could explain those problems. Recently however, some phenomena which are inconsistent with the binary model were observed (Iijima and Mammano 1981).

In the spectral range λλ5800-8750, HBV 475 shows important spectral variations between 1969 and 1974. Sometimes the “hot component” spectrum dominates (many emission lines), sometimes the “cool component” is preponderent (many molecular absorption Ti0 bands) (Andrillat 1973 – Andrillat, Houziaux 1976).

On August 4 1974, June 6 1975 and August 9 1981, we have extended the observations up to l.lμ (fig.l) (Haute Provence Observatory 193 Telescope – Spectro ROUCAS + Image tube – dispersion 230 A.mm-1).

Figure 1 shows the low resolution IUE spectra of HBV 475 during 1979-81. Whereas the May 1981 spectrum looks very similar to that of June 1979, there is a clear difference in the August 1980 spectrum when the star was brighter. The strength of the NV multiplet at 1240 A surpasses those of the preceeding and succeeding years by at least a factor 4. A first glance at the continuum and the strongest lines suggests a strong activity increase between June 1979 and August 1980, followed by a decrease to the 1979 level by May 1981. Closer inspection shows that neither CIII]λ1908 nor NIII]λl750 followed that activity pattern, but rather decreased steadly in their fluxes. Thus in June 1979 CIII]λ1908 showed the same flux as HeIIλ1640, whereas in May 1980 CIII] was weaker by a factor two. The 0Iλ1304 and MgIIλ2800 multiplets show the same behaviour as HeII, CIV and NV.

AG Draconis contains a relatively early cool component. Quoted spectral types range from dG7 (Wilson 1943) to K3III (Boyarchuck 1969). Most recently Smith and Bopp (1981) adopt G7IIIe. The optical spectrum shows in emission the permitted lines of hydrogen and helium, both neutral and singly ionized. At various times the spectrum of the late type component has been heavily veiled by a blue continuum and numerous lines of various stages of ionization of iron have been seen, including the 6830 A feature which Allen (1980) attributes to Fe VI. On the other hand, on a KPNO echelle spectrum taken by one of the current authors (CMA) in 1977 August, the late giant spectrum was very sharp and no iron or forbidden lines were present. The lack of the forbidden lines identifies AG Dra as a high density case and thus it conforms to the spectral type-density correlation found by Allen (1980).

The high resolution ultraviolet spectrum of AG Dra was observed with IUE in April and August 1981 at phases 0.50 and O.69 according to the Meinunger (1979, Inf. Bull. Var. Stars No.1611) U-light curve. The UV spectrum of the star appears rather different from that of the other classical symbiotic stars. The low resolution IUE spectrum of AG Dra shown in figure 1. The continuum is rather strong with respect to the emission lines and detectable at high resolution. Many intense interstellar lines are present, in spite of the low reddening of the star (E(B-V)=0.06, according to the depth of the 2200A interstellar band).

AG Dra is an interesting symbiotic star, on account of its very high negative velocity and its earlier spectral type among the symbiotic stars. This star has been classified as dG7 (Wilson,1943), K1 II (Roman,1953) and K3 III (Boyarchuk,1966). It has a variable radial velocity.

During summer 1981, spectroscopic observations of AG Dra were performed at the Haute-Provence Observatory using the Marly spectrograph with a dispersion of 80 A mm-1 at the 120 cm telescope and using the Coudé spectrograph of the 193 cm telescope with a dispersion of 40 A mm-1. Professor Ch. Fehrenbach very kindly given me a plate of the star which he had taken in July,1966, using the coudé spectrograph of the 193 cm telescope with a dispersion of 40 A mm-1.

Ultraviolet spectra acquired with the International Ultraviolet Explorer (IUE) of SY Mus = HD 10036 on 20 September 1980 and 11 June 1981 indicate a substantial enhancement of UV emission over a nine month period. The general UV flux level appears to have increased by approximately one order of magnitude between the first and second observing epochs. The strong ultraviolet continuum evident throughout the entire IUE spectral range λλ1200-3200 A on 11 June 1981 is closely approximated by a star with Teff = 40,000 K, where previously on 20 September 1980 the continuum distribution presented a more complex structure that is possibly explained by a combination of thermal emission from an early type main sequence star, and nebular recombination emission (Michalitsianos et al. 1981).

With Mayall’s discovery of the eclipsing nature of AR Pavonis = CD-66°3307, a nearby unique opportunity to directly probe the structure of the symbiotic binary became available. Few eclipsing systems have been detected among the symbiotics and AR Pav is fortunately bright enough to be observed spectroscopically at Coudé dispersions.

The light history of AG Peg (HD 207757) is characterized by a ~3 mag brightening which took place during 1850-70 followed by a slow decline ever since. In recent times the V magnitude has shown variations between 7.7 and 8.8, and a semi–regular behaviour with maxima 600 to 700 days apart (Mattei 1981). The optical spectrum and its time variation was studied among others by Boyarchuk (1967) and Hutchings et al. (1975) who suggested the presence of a binary system consisting in an M type giant and a WN6 companion surrounded by a nebular region.

We have obtained the first high dispersion observations of RX Puppis in the wavelength region 1200 - 3200 A with the “International Ultraviolet Explorer” (IUE). The anomalies we observed in lines such as He II, C III], C IV, N III], N IV], 0 III], and Si III], that show split line profiles, Doppler displaced component(s) suggest dynamic activity in circumstellar material that probably has the form of rings and/or gas streamers between the cool giant and the hot companion, the Mg II lines show P-Cygni structure arising in the Mira primary. The continuum cannot be due to a star earlier than A0 II and it may arise in an accretion disk around the hot secondary. Moreover, the line emission requires photoionization either from a hot subdwarf or the inner accretion disk.