A photometric and spectroscopic study of WW And - an Algol-type, long period binary system with an accretion disc

TL;DR

This study combines spectroscopic and photometric data to model WW And as a semidetached binary with an accretion disc, providing new insights into its mass ratio and disc structure.

Contribution

First detailed radial velocity curve of WW And's primary and a comprehensive model of its accretion disc and binary system.

Findings

Spectroscopic mass ratio q-spec = 0.16 +/- 0.03

Accretion disc radius determined from H-alpha emission

Consistent model of WW And as a semidetached system with an optically thick inner disc

Abstract

We have analyzed the available spectra of WW And and for the first time obtained a reasonably well defined radial velocity curve of the primary star. Combined with the available radial velocity curve of the secondary component, these data led to the first determination of the spectroscopic mass ratio of the system at q-spec = 0.16 +/- 0.03. We also determined the radius of the accretion disc from analysis of the double-peaked H-alpha emission lines. Our new, high-precision, Johnson VRI and the previously available Stromgren vby light curves were modelled with stellar and accretion disc models. A consistent model for WW And - a semidetached system harbouring an accretion disc which is optically thick in its inner region, but optically thin in the outer parts - agrees well with both spectroscopic and photometric data.