Common Envelope Evolution: Too stochastic to be deterministic
Abstract
I argue for significant stochastic behavior in the common envelope evolution (CEE) of cool giants and main-sequence companions to the degree that it is almost impossible to know the exact CEE outcome of an individual binary system from the average properties of the stars and their initial orbit. I start with two observational properties of post-CEE planetary nebulae: many have jet-shaped morphologies, and they show a wide variety of morphologies. The first suggests that the standard CEE model should include jets, and the second shows that the CEE has a wide variety of evolutionary routes; for example, jets can be launched before, during, and/or after the main CEE phase. I show that the properties of the disk with which the main-sequence companion enters the CEE depend sensitively and stochastically on the pulsations and convection of the giant star. Pulsations and giant-envelope convection stochastically determine the evolution of the accretion disk inside the envelope. The stochastic nature of the accretion disk properties implies that jet power is also stochastic. Adopting the view that jets play a major role in CEE outcomes, I conclude that the CEE outcome is stochastic. I conclude that the CEE efficiency parameter alpha(CE) has little merit for individual systems, although it still has meaning in population synthesis and other studies of large populations.
Related
- The Common Envelope Evolution Outcome. III. the Improvement of Stellar Binding Energy with the Envelope Residual
- Planets surviving common envelope evolution should be rare, massive, and orbit very close to their host star
- Stellar black hole binaries from two common envelope evolution phases in triple stellar systems
- Effect of Neutron Star Jets on Common Envelope Evolution
- Simulating the convection in red super-giant stars: wobbling jets in common envelope evolution
BibTeX
@misc{soker2026common,
title = {{Common Envelope Evolution: Too stochastic to be deterministic}},
author = {Noam Soker},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.37718},
eprint = {2609.37718},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.37718},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Common Envelope Evolution: Too stochastic to be deterministic
AU - Noam Soker
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2609.37718
UR - https://arxiv.org/abs/2609.37718
AB - I argue for significant stochastic behavior in the common envelope evolution (CEE) of cool giants and main-sequence companions to the degree that it is almost impossible to know the exact CEE outcome of an individual binary system from the average properties of the stars and their initial orbit. I start with two observational properties of post-CEE planetary nebulae: many have jet-shaped morphologies, and they show a wide variety of morphologies. The first suggests that the standard CEE model should include jets, and the second shows that the CEE has a wide variety of evolutionary routes; for example, jets can be launched before, during, and/or after the main CEE phase. I show that the properties of the disk with which the main-sequence companion enters the CEE depend sensitively and stochastically on the pulsations and convection of the giant star. Pulsations and giant-envelope convection stochastically determine the evolution of the accretion disk inside the envelope. The stochastic nature of the accretion disk properties implies that jet power is also stochastic. Adopting the view that jets play a major role in CEE outcomes, I conclude that the CEE outcome is stochastic. I conclude that the CEE efficiency parameter alpha(CE) has little merit for individual systems, although it still has meaning in population synthesis and other studies of large populations.
ER -