A critical review of period analyses and implications for mass exchange in W UMa eclipsing binaries: Paper 4

This is the fourth paper in the series of analyses of times of minimum and period variations in W UMa eclipsing binaries, and the implications for mass exchange in these systems. In this paper, the systems discussed in Papers 1–3 for which analyses are relatively complete are sorted into three sections, arranged in order of degree of confidence that mass exchange occurrence is established and that the present rate of exchange has been determined. The higher-confidence systems are: 44 Boo, RZ Cam, VW LMi, AU Ser; the intermediate-confidence systems are: TY Boo, V1191 Cyg, AP Leo, ER Ori; and the lower-confidence systems are: AB And, XY Boo, AC Boo, AH Cnc, VW Cep, EZ Hya, XY Leo, W UMa, and GR Vir. A fourth section describes promising cases that require additional data and/or analyses. For the higher-confidence systems, selected analyses of the times of minimum and of the most comprehensive light curve (LC) and radial velocity (RV) suites of data have yielded mean mass changes to the more massive component of dM₁/dt = +2.37 (13) × 10⁻⁷ M_ʘ/y for 44 Boo, +4.00 (14) × 10⁻⁸ M_ʘ /y for RZ Com, +2.53 (7) × 10⁻⁷ M_ʘ /y for VW LMi, and -1.98 (11) × 10⁻⁷ M_ʘ /y for AU Ser.