The extraordinary LBV/WR system HD 5980

TL;DR

This paper models the tidal interactions and wind dynamics in the LBV/WR binary system HD 5980, revealing phase-dependent energy dissipation and asymmetric outflows that influence wind-wind interactions.

Contribution

It introduces a model of tidal flows and wind interactions in HD 5980, highlighting the importance of non-stationary and asymmetric wind structures in such systems.

Findings

Energy dissipation rates vary with orbital phase.

Strongest wind interactions may occur after periastron.

Localized polar outflows are predicted during the orbit.

Abstract

The LBV/WR system HD 5980 contains a short-period, eccentric binary system with interacting stellar winds. In this paper we summarize results from model calculations of the tidal flows on the LBV component showing that energy dissipation rates, E-dot, associated with turbulent viscosity are orbital-phase dependent as well as variable over the stellar surface. We speculate that if E-dot contributes towards driving mass-loss, the strongest wind-wind interaction effects may occur after periastron passage. In addition, the model suggests the presence of stronger outflows localized at polar angles theta~30 --50 degrees during part of the orbital cycle. Thus, the analysis of wind-wind interactions in this system requires that models be revised to incorporate non-stationary and asymmetric wind structures.