Results of the high dispersion spectroscopic observations on HBV 475, V1016 Cyg, and HM Sge are presented. Due to yearly observations of HBV 475 since 1981, radial velocities which have been measured from Hα and Hγ can be explained by a bipolar like non-spherical flow combined with the rotation. Highly resolved profiles of Hα, [FeVII]λ6087, [0III] λλ4959,5007, and HeIIλ4686 are obtained from V1016 Cyg and HM Sge as well as HBV 475. Characteristic differences of them can be seen among these symbiotic stars.

EG And is a symbiotic binary system. The cool component is an M3 III star, the hot one is a subdwarf with temperature 60 250 K and luminosity 1.45 L⊙ (Boyarchuk, 1985). The eclipsing nature of the system suggested from UV spectroscopy by Oliversen et al. (1985) was confirmed photometrically by Chochol et al. (1987). The circular spectroscopic orbit of cool component determined by Oliversen et al. (1985) supposing the orbital period 470 days leads to f(m) = 3.2×10−2 M⊙ and detached configuration.

We report observations at opposite quadratures of the interacting symbiotic binary EG Andromedae (HD 4174, Period = 470d). Correcting for absolute motion at the system, it appears that many of the nebular lines arise from material that moves with the red giant star. The He II feature appears to track the hot component. It may be possible to use this feature in other, similar systems in order to “pin-down” the mass ratio.

The symbiotic variable UV Aur was observed by Merrill (1941) and Sanford (1944, 1949). UV Aur is classified as C8 ep carbon variable (Kukarkin et al. 1969) with a hot white dwarf and surrounding nebula. Infrared photometric observations have been done by Allen (1982), Noguchi et al. (1981) and Kenyon and Gallagher (1983) in the near infrared region and by woolf (1973) at 2.2 micron to 20 micron region. UV Aur has also been observed by IRAS and IUE Satellite. Polarimetry of UV Aur has been studied by Khudyakova (1985) in the optical region.

Of the more than 100 symbiotic stars now known in our Galaxy, only two have previously been reported to contain carbon stars as their cool components. We here present observations of a third such object, which we wish to call Weaver’s star since Weaver (1972) first identified it as a symbiotic.

BI Crucis is a 12 mag star whose optical spectrum is characterized by a red continuum and variable emission line spectrum (Allen 1974, Henize and Carlson 1980, Whitelock et al. 1983). In order to investigate its symbiotic character on 18 February 1983 we have obtained at the 1.5m ESO telescope a 59 Å/mm spectrogram of the 5700-6900 Å region. BI Cru displayed a very rich emission line spectrum with very strong Hα. and prominent HeI (5876 and 6678Å) lines. Several FeII lines are also present which appear optically thick (Figure 1). A few absorption features (NaI, 6269-84) of interstellar origin are present. However, we find no trace of TiO bands (or of neutral atoms) in spite of Allen’s (1974) finding, but in agreement with Whitelock et al. (1983). Allen (priv. comm.) remarks that in his spectrum there are slight ‘waves’ in the continuum that looked like TiO absorptions. Thus the symbiotic nature of BI Cru is mostly based on its long term IR variability (T≅280 d, Whitelock et al. 1983). They also found the first overtone vibration rotation band of CO at 2.3 μm in emission. The CO emission band was recently resolved by McGregor et al. (1987). This is the first observation of CO in emission in a symbiotic object. The red continuum is more probably a highly reddened hot continuum. We note that a weak continuum is present in the LWR IUE image taken in March 1981 (Fig.2). This spectrum also shows a few emission lines of Mgll and FeII. BI Cru is also a strong IRAS source. Following the model of Kenyon et al. (1986) for D-type symbiotics, the cool component of BI Cru could be reddened by circumstellar dust. A high resolution ESO CAT/CES red spectrum shows Hα doubled by a central absorption extending from −38 to −290 km/s with respect to the center of the emission line which suggests the presence of intermediate velocity winds like in other symbiotic stars.

A recent analysis of all available photometric data has resulted in a new ephemeris for BF Cyg: MIN=JD 2415058 + 756.8E. Simultaneously, optical spectra collected in 1979–1986 showed periodic changes of all emission lines (Mikolajewska 1987; Mikolajewska & lijima 1987). It is interesting that the forbidden lines of [OIII] varied in antiphase to the permitted emission lines and optical brightness.

IUE spectra taken in 1979–1981 showed a strong hot continuum and high ionization resonance emission lines of NV, SilV CIV, intercombination lines of NIV], NIII], SiIII], CIII] and OIII] as well as Hell emission. The observed λ2200Å interstellar absorption band suggests E(B-V)≃0.3. Taking into account the interstellar reddening distribution in the vicinity of BF Cyg (Lucke 1978; Mikolajewska & Mikolajewski 1980), the observed extinction implies a distance d≲1.5kpc. This distance is in good agreement with the observed low value of the systemic radial velocity (∼15 km/s, Fig.1) of BF Cyg and the standard galactic rotation law. The standard extinction curve with E(B-V)=0.3 (Seaton 1979) was used for reddening correction of the spectra. The UV continuum of BF Cyg can be interpreted as a combination of a hot subdwarf (Teff≃60000K, L≃2500L⊙ for d=1.5kpc) and hydrogen bf+ff emission (Te≃10000K). The emission measure of the nebular (bf+ff) continuum varied from ∼4×1059cm−3 at maximum to ∼1059cm−3 at minimum. Assuming cosmic abundance of Si/C the observed SiIII]/CIII] line ratio implies ne≃2×l010cm−3 at the photometric maximum and ne≃3×109cm−3 at the minimum. We assume that these values are representative of the region where the bulk of the HI Balmer and intercombination line emission is produced. The ratio of NV(1240)/NIV(1720) gives Te(NV)≃11500K close to the value derived for the Balmer emission region from the UV continuum fit.

In this paper we provide preliminary results of multifrequency observations of BF Cyg carried out in July 1986. The ultraviolet spectra were obtained on July 26, 1986 using the IUE satellite. The optical observations were made at the Observatorio del Roque de los Muchachos (La Palma, Canary Islands) in July 1986 during the night 13/14 using the Isaac Newton 2.5m telescope with the Intermediate Dispersion Spectrograph (IDS, 500 mm camera) and the Image Photon Counting System (IPCS). The infrared observations were made during the night 13/14 of July, 1986, at the Observatorio del Teide (Tenerife, Canary Islands) using the Carlos Sanchez 1.5m telescope and an infrared single-channel photometer with an InSb detector.

Recent photometric and spectroscopic observations suggest AX Per might be an eclipsing binary with a period of about 682 days (Kenyon 1986 and references therein). The analysis of optical spectra taken during 1979-1986 has shown periodic minima in all observed permitted lines and a lack of any periodicity in the forbidden lines (Mikolajewska 1987; Mikolajewska & lijima 1987). A comparison of the available radial velocities with these intensity variations shows that the behaviour of emission lines is consistent with the eclipse interpretation, however the minima (especially in HI and HeI) are too broad to be consistent with eclipses even by a Roche lobe filling red giant. In the following, the UV behaviour of AX Per is analysed using IUE spectra collected during the period 1979-1984.

He 2-104 has been classified as both a planetary nebula and as a symbiotic star. Optical and ultraviolet spectra and CCD images have been obtained in order to learn more about the evolutionary state of this object. The spectra of the object indicate that it could be either a symbiotic star or a very high excitation planetary nebula. The CCD images show a nebulosity with a radius of about 4 seconds of arc and faint bipolar outer structures extending out approximately 25 seconds of arc from the center of the nebula.

The evolutionary origins of symbiotic stars containing (i) disk-accreting main sequence stars, (ii) wind-fed, shell-burning white dwarfs, and (iii) disk-accreting neutron stars are described. Of particular interest are those white dwarf systems which have orbital periods too short to have escaped tidal mass transfer prior to becoming symbiotics. We show here that, under suitable circumstances, low-mass, long period binaries may undergo quasi-conservative mass transfer, rather than evolving through common envelope evolution to the cataclysmic variable state, thus accounting for the existence of these systems. Approximate expressions are given for the lifetimes, and relative efficiencies (mass accreted/mass of donor) for different modes of interaction among symbiotic binary systems.

An examination of the existing observational material on all the objects classified as recurrent novae, reveals that only T Pyx, U Sco, T CrB and RS Oph deserve such a classification. We review the properties of outbursts powered by thermonuclear runaways and accretion events and determine their observational consequences. We conclude that the outbursts of T CrB and RS Oph are very probably caused by accretion events from a giant companion onto a main sequence star. The outbursts of T Pyx and U Sco may be powered by thermonuclear runaways on the surface of white dwarfs with masses close to the Chandrasekhar limit. However, some questions, in particular regarding the composition of the accreted material in U Sco remain to be answered.

VLBI observations of RS Ophiuchi during its 1985 outburst enable us to start to disentangle the multiple component radio emission. It appears that the emission at low frequencies was predominantly non–thermal, whereas at high frequencies the emission is most likely thermal. It is then possible to probe the physical properties of the remnant.

Spectral observations obtained soon after the 1987 brightening of U Sco support a thermonuclear runaway model for outbursts of this object. Spectra later in the decline are, however, more characteristic of a hot accretion disc. These observations are reconciled in a model where the low-mass high-velocity shell ejected from the surface of the white dwarf collides with the accretion disc causing it to brighten.

ζ, Aur binaries are wide eclipsing systems (P ≃ 1...10 yrs), containing a late supergiant primary (G to M type) and an early dwarf companion (A0 V... B3 V ). Some recent studies of wind phenomena (mass loss rates), chromospheric properties and wind acceleration (of the supergiant) as well as wind accretion phenomena introduced by the gravitational interaction with the companion are presented, summarizing previous work of the Hamburg ’binary wind team’(mainly D. Reimers, R. Baade, A. Che-Bohnenstengel, K. Hempe, K.-P. Schröder).

The last session of the Colloquium was Chaired by Harry Nussbaumer and opened with statements from members of a panel comprised of Livio, Mikolajewska, Luud, Viotti, Magalliaes, Slovak, Kwok and Whitelock. Viotti began by comparing the available data for symbiotics historically and since IAU Colloquium 70 in 1981. He emphasized new UV, X-ray, infrared and radio observations. He also sketched the recent history of wavelength specific publications. Whitelock stated that it now seems clear all D-types probably contain Miras and that S-types do not evolve into D-types. Luud stated that his group intends to continue its near infrared observations with the 2 meter at Tartu, and that it is important to confirm conclusions based on IRAS data. He mentioned that masses for the Miras are needed given the discrepancy between observed and evolutionary masses.

After a brief description of the difficulties and pitfalls of finding a correct interpretation of the symbiotic phenomenon, I emphasize what I consider to be the highlights of the meeting. Directions for future research are indicated.