The Eclipsing Binary System W-Crucis

PhotoelectricUBV photometry of the long period southern eclipsing binary system W Cru gathered over an 18-mo period in 1984–1985 is presented and examined. The light curve is characterized by continuous 'Beta Lyrae'-like variation: unexpected in such a long period (∼198.5 days) system; together with peculiar irregularities, of the order of 0.1 mag (or more inU) and time-scales of a few days. A high mass model (total mass ∼70M_⊙) could be made to be roughly consistent with the data, though alternative models of much lower mass are also possible, and may turn out to be preferable, in terms of goodness-of-fit, as well as for theoretical reasons. The low mass models would require, though, the more massive component to be unseen (as now generally supposed for β Lyrae itself). The photometry alone, or even combined with a known spectroscopic mass-function, seems unlikely to be able to furnish a single definitive 'solution', and more guidelines from reliable theoretical expectation may prove helpful in interpreting the data.