IUE spectra of VV Cep have been obtained in 1978 and 1979 during the chromospheric phase of the eclipse. The profiles of the Mg II resonance lines differ from one another and this peculiarity, common to other M type supergiants, is examined. The value of Mv derived from the extension of the Wilson and Bappu relation to Mg II lines is compared with other determinations. The variation of the absolute flux in the 1200-2000 Å range is presented.

Ultraviolet observations of the Zeta Aurigae systems appear to have several advantages over comparable visual wavelength studies. A wide range of large optical depth resonance lines of abundant species permit the study of the supergiant atmosphere and circumstellar environment at virtually all phases. The International Ultraviolet Explorer satellite (Boggess, et al., 1978) is well suited to obtaining spectra between 1150 and 3200 A, although the competition for observing time is non-negligible.

A brief survey of known eclipsing binaries and cataclysmic variables in globular cluster fields is presented. None of the 47 known or suspected eclipsing variables is a promising candidate, although a very few remain possible members. V101 in M5 is a good candidate for membership, among 5 known or suspected dwarf novae. Three novae have been discovered in globular cluster fields, of which two are almost certainly members. Attention is also called to the eclipsing binary V80, a system which appears to contain an RRc variable, in the dwarf spheroidal galaxy in Ursa Minor.

The present paper is a progress report on a search for spectroscopic binaries among central stars of planetary nebulae. In the last few years it has become clear that such a program may result in a significant improvement of the available information about the central stars, and, whatever the outcome, it will certainly help to test current theoretical work on the origin of planetary nebulae.

Recent observations of nuclei of planetary nebula have shown that some of the central stars are binaries and even close binaries with periods of hours to few days.

The temperature, surface gravity, and abundances derived for this halo B star by Danziger and Jura (1970, Ap.J., 161, 997) show that it is a field suprahorizontal branch star very similar to B29 in M13. The only difference is that HD137569 has a higher (solar) C abundance. We find that HD137569 is a spectroscopic binary with P=529.8(2) days, Vo=45.0(2) km/s, K=16.2(3) km/s, e=0.12(2), ω=233°(10), and T=JD2441922(14). The parenthesized quantities are the uncertainties (probable errors) of the last digits of the elements.

During the last four days we have seen a number of interesting and important results concerning problems which will certainly attract our attention in the years to come. To give examples, I would mention: formation of binaries, structure of contact systems, evolution with a common envelope, planetary nebulae with CBS nuclei, starspots and magnetic fields. As for individual objects, SS 433 would be obviously No. 1 on our list of highlights.

I present here some thoughts on the theory and observation of interacting binary systems. The complex physical processes possible in these systems make our present understanding inconclusive. New types of observation (X-ray, EUV, radio) present new challenges to the theoretician. I discuss here those problems which seem to me to hold the most promise for future progress and relate the papers in this conference to these problems.