Apsidal motion in southern eccentric eclipsing binaries: GL Car, QX Car, NO Pup and V366 Pup

The study of apsidal motion in eccentric eclipsing binaries (EEB) provides an important observational test of theoretical models of stellar structure and evolution. The Southern hemisphere contains many interesting and also neglected binary systems. New accurate photoelectric times of minimum light have been obtained for the detached early-type Southern hemisphere EEB GL Car (P = 2.42 d, e = 0.15), QX Car (4.48 d, 0.15), NO Pup (1.26 d, 0.13) and V366 Pup (2.48 d, 0.47). The O-C diagrams are analysed using all reliable timings found in the literature and improved or new values for the elements of the apsidal motion are computed. We find more precise, relatively short periods of apsidal motion of about 25.2, 362, 38.3 and 285 yr and corresponding internal structure constants, log k(2), - 1.88, - 2.08, - 2.32 and - 2.38 for GL Car, QX Car, NO Pup and V366 Pup, respectively, with the assumption that the component stars rotate pseudo-synchronously. The relativistic effects are small, being about 3 - 12 per cent of the total apsidal motion rate in all systems..