Photometric And Spectroscopic Binary Systems

Photometric and Spectroscopic Binary Systems

Our conference - opening today - has two aims in view: first, to commemorate some milestones in the development of the studies of close binary systems whose anniversaries fall in these years, as well as to take stock of our present knowledge accumulated through out preceding decades, in order to consider where do we go from here. This summer, 310 years will have elapsed since the first ec lipsing binary - Algol - was discovered in Bologna by Geminiano Montanari (1633-1687) to be a variable star; and 198 years have gone by since John Goodricke of York (1764-1786) established the fact that Algol's light changes were periodic. Moreover, it is al most exactly (to a month) now 100 years since Edward Charles Pickering (1846-1919) of Harvard Observatory in the United States took the first steps towards the development of systematic methods of analysis of the light changes of Algol and related systems - a topic which will constitute the major part of the programme of our present conference. The three dates recalled above illustrate that the discoverers of such celestial objects and observers of their light changes have been systematically ahead of the theoreticians endea vouring to understand the significance of the observed data by de cades and centuries in the past - a fact which, incidentally, con tinues to hold good (albeit with a diminishing lead-time) up to the present.

Literature 1981, Part 1

The ∆a photometric system

This book describes the characteristics and applications of the Δa photometric system, which measures the stellar flux at around 520 nm. Since its introduction in 1976 by Hans-Michael Maitzen, the Δa system has not only been successfully applied to the classical chemically peculiar stars of the upper main sequence, but also to galactic and extragalactic star clusters. New possible applications for studying galaxies, quasars and other astrophysical objects of interest are discussed.