Algol-type binaries. IX. V548 Cyg

We model the UV light curve together with two previously published (B and V) light curves, primary star radial velocities, and eclipse timings in a unified multi-data-type solution and determine orbital parameters and absolute dimensions. Timing residuals hint at the presence of a third star in the system.

This star is possibly the source of the third light that is needed to obtain a good fit to each of the light curves simultaneously. The light-time oscillation in the timing residuals has a period of either ~19 or ~46years. The third body orbit inclination would have to be low (23{deg} or 15{deg}, respectively) for the third star to have a mass of ~1.5M_{Sun}_, which would be expected for a main-sequence star of color B-V~0.32, as determined from the light curve solution.