Dust formation during the interaction of binary stars by common envelope

TL;DR

This study uses numerical simulations to investigate dust formation during common envelope interactions of binary AGB stars, revealing early dust grain formation, dusty shell development, and quantifying dust yields without significantly affecting mass loss or orbital dynamics.

Contribution

First explicit calculation of dust formation and growth during common envelope interactions of binary AGB stars.

Findings

Dust grains appear within 1-3 years after CE onset.

A high-opacity dusty shell forms, enlarging the photosphere.

Total dust yield is approximately 0.0082 to 0.022 solar masses.

Abstract

We performed numerical simulations of the common envelope (CE) interaction between two intermediate-mass asymptotic giant branch (AGB) stars and their low-mass companions. For the first time, formation and growth of dust in the envelope is calculated explicitly. We find that the first dust grains appear as early as $\sim$1-3 yrs after the onset of the CE, and are smaller than grains formed later. As the simulations progress, a high-opacity dusty shell forms, resulting in the CE photosphere being up to an order of magnitude larger than it would be without the inclusion of dust. At the end of the simulations, the total dust yield is $0.0082~M_{\odot}$ ($0.022~M_{\odot}$) for a CE with a $1.7~M_{\odot}$ ($3.7~M_{\odot}$) AGB star. Dust formation does not substantially lead to more mass unbinding or substantially alter the orbital evolution.