Common Envelope Wind Tunnel: Range of Applicability and Self-Similarity in Realistic Stellar Envelopes

TL;DR

This paper investigates the applicability of a simplified drag formalism, based on wind tunnel simulations, to model the common envelope phase in binary star evolution, demonstrating its broad applicability and self-similar behavior across different stellar masses and ages.

Contribution

It introduces a semi-analytical framework incorporating wind tunnel simulation results to model common envelope evolution across various stellar types, highlighting its broad applicability and self-similarity.

Findings

The drag formalism applies across a wide range of stellar masses and ages.

The formalism exhibits self-similar behavior across different regimes.

Limitations are identified based on global binary properties and local structures.

Abstract

Common envelope evolution, the key orbital tightening phase of the traditional formation channel for close binaries, is a multistage process that presents many challenges to the establishment of a fully descriptive, predictive theoretical framework. In an approach complementary to global 3D hydrodynamical modeling, we explore the range of applicability for a simplified drag formalism that incorporates the results of local hydrodynamic "wind tunnel" simulations into a semi-analytical framework in the treatment of the common envelope dynamical inspiral phase using a library of realistic giant branch stellar models across the low, intermediate, and high mass regimes. In terms of a small number of key dimensionless parameters, we characterize a wide range of common envelope events, revealing the broad range of applicability of the drag formalism as well its self-similar nature across mass regimes and ages. Limitations arising from global binary properties and local structural quantities are discussed together with the opportunity for a general prescriptive application for this formalism.