Dust Formation in Common Envelope Binary Interaction -- I: 3D Simulations Using the Bowen Approximation

TL;DR

This study uses 3D simulations with the Bowen approximation to explore dust formation and its effects during common envelope binary interactions, revealing significant impacts on envelope expansion and observable properties.

Contribution

It introduces the use of 3D smoothed particle hydrodynamics simulations with Bowen dust opacity approximation to analyze dust effects in common envelope evolution.

Findings

Dust-driven winds cause slight envelope unbinding.

Recombination energy influences dust effects on the envelope.

Dust significantly enlarges the post-inspiral photosphere.

Abstract

We carried out 3D smoothed particle hydrodynamics simulations of the common envelope binary interaction using the approximation of Bowen to calculate the dust opacity in order to investigate the resulting dust-driven accelerations. We have simulated two types of binary star: a 1.7 and a 3.7 $M_{\odot}$ thermally-pulsating, asymptotic giant branch stars with a 0.6 $M_{\odot}$ companion. We carried out simulations using both an ideal gas and a tabulated equations of state, with the latter considering the recombination energy of the envelope. We found that the dust-driven wind leads to a relatively small increase in the unbound gas, with the effect being smaller for the tabulated equation of state simulations and for the more massive primary. Dust acceleration does contribute to envelope expansion with only a slightly elongated morphology, if we believe the results from the tabulated equation of state as more reliable. The Bowen opacities in the outer envelopes of the two models, at late times, are large enough that the photosphere of the post-inspiral object is about ten times larger compared to the same without accounting for the dust opacities. As such, the prediction of the appearance of the transient would change substantially if dust is included.