A critical review of period analyses and implications for mass exchange in W UMa Eclipsing Binaries: Paper 1

This is the first of a series of four papers, the goal of which is to identify the overcontact eclipsing binary star systems for which a solid case can be made for mass exchange. To reach this goal, it is necessary first to identify those systems for which there is a strong case for period change. We have identified 60 candidate systems; in the present paper and in two succeeding papers we will discuss the individual cases. For each system, we will present a detailed discussion and evaluation concerning the observational and interpretive material presented in the literature. An eclipse timing diagram (or diagrams), commonly referred to as an “O–C diagram”, using the latest available data will accompany each discussion. In paper 3, we will also present a table of marginal and rejected cases. In paper 4, we will present a discussion of the mechanisms that can effect period change and which of the systems presented can be reliably concluded to exhibit mass exchange.