Evolution of massive stars is dominated by interactions within binary
systems. Therefore, it is necessary to investigate all forms of interaction in
binary systems that may affect the evolution of the components. One of such
`laboratories' is the massive eccentric binary system MACHO80.7443.1718
(ExtEV). We examine whether the light variability of the ExtEV can be explained
by a wind-wind collision (WWC) binary system model. We conducted an analysis of
broadband multi-color photometry of ExtEV, time-series space photometry from
TESS, ground-based Johnson UBV photometry, and time-series spectroscopy. We
fitted an analytical model of light variations to the TESS light curve of
ExtEV. We rule out the possibility of the presence of a disk around the primary
component. We also argue that the non-linear wave-breaking scenario is not
consistent with the observations of ExtEV. We refine the orbital parameters of
ExtEV and find evidence for the presence of a tertiary component. Using
evolutionary models we demonstrate that the primary component's mass is between
25 and 45M⊙. We successfully reproduce light curve of ExtEV with our
model, showing that the dominant processes shaping its light curve are
atmospheric eclipse and light scattered in the WWC cone. We also estimate the
primary's mass-loss rate due to stellar wind for 4.5⋅10−5M⊙yr−1. ExtEV is not an extreme eccentric
ellipsoidal variable, but an exceptional WWC binary system. The mass loss rate
we derived exceeds theoretical predictions by up to two orders of magnitude.
This implies that the wind in the system is likely enhanced by tidal
interactions, rotation, and possibly also tidally excited oscillations. ExtEV
represents a rare evolutionary phase of a binary system that may help to
understand the role of a companion-driven enhanced mass loss in the evolution
of massive binary systems.Comment: Submitted to Astronomy&Astrophysics, 23 pages, 15 figures, 9 table