X-RAY BINARY UNIFIED ANALYSIS - PULSE RV APPLICATION TO VELA X1 GP VELORUM/

A procedure for simultaneous analysis of multiple kinds of observation s is developed for binaries that contain X-ray pulsars, A wide variety of observation types might be included, although we consider only vel ocity: pulse and light: velocity: pulse cases at present. The model op erates with equipotentials and can accommodate non-synchronous rotatio n and eccentric orbits. The duration condition imposed by observed X-r ay eclipses is incorporated as an embedded constraint, so that only so lutions consistent with the eclipse duration are found. Relations need ed for the method of differential corrections in least-squares solutio ns are specified, and we apply the Marquardt scheme for improvement of solution convergence. Parameters of Vela X1: GP Velorum are obtained from seven combinations of pulse and radial velocity data. The estimat ed masses are thereby put into some perspective, especially for the ne utron star. The mass of the supergiant (m sin(3) i) now ranges only +/ -5 per cent from the mean of seven results, although the uncertainty i n i makes the actual mass range larger. We discuss the determinacy of certain parameters and their historical consistency. For example, the systemic radial velocity differs among spectroscopic data sets by more than 20 km s(-1). We show that, contrary to published assertions, the orbital inclinations of high-mass X-ray binaries are essentially inde terminable by the usual methods, although lower limits to inclination may be meaningful for some examples.