[en] Observations of symbiotic stars in the far UV have provided important information on the nature of these objects. The canonical spectrum of a symbiotic star, e.g. RW Hya, Z And, AG Peg, is dominated by strong allowed and semiforbidden lines of a variety of at least twice ionized elements. Weaker emission from neutral and singly ionized species is also present. A continuum may or may not be present in the 1200 - 2000 A range but is generally present in the range 2000 - 3200 A range. The suspected hot subdwarf continuum is seen in some cases in the range 1200 - 2000 A (RW Hya, AG Peg, SY Mus). The presence of an accretion disk is difficult to demonstrate and to this date the best candidate for accretion to a main sequence star remains CI Cyg. A number of equations have been derived by the author that can yield the accretion parameters from the observable quantities. Boundary layer temperatures approximately 10⁵ K and accretion rates approximately > 10^-5 solar masses/yr are required for accreting main sequence companions. To this date, though, most of the symbiotics may only require the presence of a approximately 10⁵ K hot subdwarf. (Auth.)

[en] The fact that most symbiotic starts do not have detectable radio emission is consistent with the hypothesis that the mass transfer is via Roche lobe and the optical and ultraviolet emission lines originate from the mass transfer region. However, in a number of slow novae, stellar winds from either the cool or the hot components can generate an extended circumstellar envelope from which radio emission arises. It is interesting to note that when an M-giant wind is present, there is no need for the cool component to fill the Roche lobe, and accretion can occur via the M-giant wind. The evolution of the radio spectra of some slow novae is best explained by the interaction of two stellar winds, and this is supported by the line profile analysis by Willson and Wallerstein (1981). It is clear from radio observations that in classical novae the hot-star wind dominates and in normal symbiotic systems wind is not an important element. Slow novae, being intermediate objects, may have their origins tied to the presence of a stellar wind from the cool component. (Auth.)

[en] Infrared photometry and spectroscopy of symbiotic stars is reviewed. It is shown that at wavelengths beyond 1 μm these systems are generally dominated by the cool star's photosphere and, indeed, are indistinguishable from ordinary late-type giants. About 25% of symbiotic stars exhibit additional emission due to circumstellar dust. Most of the dusty systems probably involve Mira variables, the dust forming in the atmospheres of the Miras. In a few cases the dust is much cooler and the cool component hotter; the dust must then form in distant gas shielded from the hot component, perhaps by an accretion disk. Spectroscopy at 2 μm can be used to spectral type the cool components, even in the presence of some dust emission. Distances may thereby be estimated, though with some uncertainty. Spectroscopy at longer wavelengths reveals information about the dust itself. In most cases this dust appears to include silicate grains, which form in the oxygen-rich envelope of an M star. In the case of HD 33036, however, different emission features are found which suggest a carbon-rich environment. (Auth.)

[en] Low spectral resolution observations (approximately 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 the eclipse observations, enabling the authors 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 approximately 3 magnitudes in the visual. The short wavelength spectrum lambdalambda1200-2000 A is characterized by numerous intense high excitation emission lines that become more prominent out of eclipse. The LWR wavelength range lambdalambda2000-3200 A exhibits a few more additional lines of O III, Mg II and He II that are superimposed on continuum that rises gradually with increasing wavelength. Additionally, OH emission bands are identified at lambdalambda3064, 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 lambda3646 A, and enables one to ascribe the UV continuum observed with IUE to mainly Balmer free-bound recombination emission. (Auth.)

[en] The authors report optical emission line variations in CI Cygni during the 1980 eclipse. (Auth.)

[en] The authors summarise the results of observations of the 1967-70 activity phase in the photographic spectral range (3300-4900), and of the activity phase which started in 1977 in the spectral range 6700-3400 A and 3100-1175 A, and then compare the phenomena observed during the two outbursts. (C.F./Auth.)

[en] The authors discuss observations from infrared photometry of RR Tel from 1975 to 1986. Variations with a period of about 387 days. This period, which has an amplitude of 0.6 mag at 2.2 μ, confirms suggestions that the RR Tel system contains a Mira. The suggestion is further supported by the observation of TiO in the photographic spectrum and H₂O in the infrared. As well as being a slow nova RR Tel appears to be a typical member of the subgroup of symbiotics which contain a Mira variable and an infrared dust excess. (Auth.)

[en] This article is an interim report on a survey of the symbiotic stars with the IUE satellite, both at low resolution and, for AG Pegasi and CH Cygni, at high resolution. The UV spectra, including both the emission lines and the continua, are presented and discussed. Since it is somewhat premature to draw general conclusions, the emphasis is biased towards a discussion of individual stars. AG Pegasi is used as an illustrative, albeit atypical, example. (Auth./C.F.)

[en] The observations of CI Cyg were carried out with the Torun 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). A preliminary analysis of the obtained spectra is presented. (Auth.)

[en] The light history of V1016 Cygni is divided into three distinct phases - the preoutburst phase, the phase of increasing luminosity and the quasi stationary phase - each of which is briefly discussed. The author then considers emission spectra in the infrared, radiowave, ultraviolet and X-ray regions. (C.F.)