Eclipse Scan

NASA Technical Note

Algols

When leaving the Victoria airport the day before our Colloquium, I saw a van of the Dunsmuir Lodge marked with big letters which I read as "Alcohol Colloquium". I do often make such blunders because of the global, casual, and careless way in which I read various ads, and checked myself quickly to read it correctly as "Algol Colloquium". Millions of fellow citizens could easily make the same mistake, and no apology could be expected. Even I read and hear the word alcohol more frequently than Algol, although I must say that Algols have given me more pleasure and fewer headaches over the years; in that, however, I may be a singularity, and possibly a pitiful one at that. Being appointed Chairman of the Scientific Organizing Committee, I may be deemed to be a purer" Algolist" than other investigators, although my range of active interests is much broader; and the same is true about all the 28 invited speakers and all the other participants of the Colloquium. Our interest are strongly diversified, but there are several good reasons that brought us together at this Colloquium.

Active Close Binaries

Since the 1970s symposia or colloquia devoted to recent research on close binaries have been held around the world almost annually. At meetings of the General Assembly of the International Astronomical Union this topic has also been discussed in detail at presentations in various commission meetings and also as invited talks by leading astronomers in the field. In recent years, fundamental changes have taken place in the study of close binaries due to the improvements in observational techniques, extension of observations from X-ray to radio regions of the electromagnetic spectrum, and advances in theoretical studies. For more than a decade, a group of astronomers at Ege University Observatory has been concentrating on active close binaries with particular emphasis on the behaviour of the light curves of chromospherically active systems. Thus, we decided to organize an international meeting in Western Anatolia, where this part of Turkey had been the cradle for great developments in science during antiquity. KUljadasi, located only minutes away from Ephesus, one of the seven wonders of the world, was selected to be the meeting site. Close binary systems constitute a very rich source of information about the physical properties of the component stars. Some systems are eclipsing variables, where periodic recurrences of eclipses are observed as comparatively brief decreases in the total brightness of the binary system. Precise methods of photometric observations make it possible to obtain the light variations of these systems because of eclipses and other phenomena.