Many aspects of symbiotic stars have long puzzled astronomers. For instance while most students of the subject have considered them binary, many have at different times supported single star models. The nature of their outbursts is uncertain, while the dividing line between symbiotic stars and novae is unclear. In any case doubts can even be raised as to whether a class of "Symbiotic Stars" really exists. Much new data has been obtained in recent years, in particular from the study of radiation outside the visual region. Many symbiotic stars have been studied in the UV with IUE since 1978,...

Symbiotic stars were identified spectroscopically as M giants with a very strong He II 4686 emission line. After five decades of study by many astronomers, the first internatioinal meetings devoted to symbiotics were held at the University of Colorado (Boulder) and at the Haute Provence Observatory during the Summer of 1981. These conferences emphasized exciting new results obtained by modern satellite (EINSTEIN, IUE) and ground-based observatories. Although the vast majority of the participants were already fairly sure that symbiotics are almost certainly interacting binary systems, and not...

The same kind of physics is frequently common to very different fields of Astrophysics, so experts in each of these fields have often much to learn from each others. It was therefore logical that the International Astronomical Union should sponsor a colloquium about an ion which pro duces many spectral lines that can be used as a diagnostic for many sorts of objects, and which may sometimes have a major influence on physical processes occurring in astro physical sources. The lines of singly ionized iron (FeII) are present in absorption and emission in the spectra of objects such as the Sun,...