An exploration of dust grain growth within WCd systems using an advected scalar dust model

TL;DR

This study uses numerical models with an advected scalar dust approach to explore dust grain growth in WCd binary systems, revealing how stellar wind parameters influence dust production.

Contribution

It introduces a passive scalar dust model in simulations to analyze dust growth and destruction in WCd systems, highlighting key factors affecting dust yields.

Findings

Higher stellar mass loss rates increase dust production.

Close binary orbits lead to more dust formation.

Wind shear and KH instabilities significantly boost dust yields.

Abstract

Dust production is one of the more curious phenomena observed in massive binary systems with interacting winds. The high temperatures, UV photon flux and violent shocks should destroy any dust grains that condense. However, in some extreme cases dust production yields of approximately 30% of the total mass loss rate of the stellar winds have been observed. In order to better understand this phenomenon a parameter space exploration was performed using a series of numerical models of dust producing carbon phase Wolf-Rayet (WCd) systems. These models incorporated a passive scalar dust model simulating dust growth, destruction and radiative cooling. We find that reasonable dust yields were produced by these simulations. Significant changes in the dust yield were caused by changing the mass loss rates of the stars, with a greater mass loss rate contributing to increased dust yields. Similarly, a close orbit between the stars also resulted in higher dust yields. Finally, a high velocity wind shear, which induces Kelvin-Helmholtz (KH) instabilities and wind mixing, drastically increases the dust yields.