Work

Excitation of Post-asymptotic Giant Branch Star Binary Eccentricity by Massive Polar-aligned Circumbinary Disks

Year: 2025

Type: article

Abstract: Many post-asymptotic giant branch star binaries are observed to have relatively high orbital eccentricities (up to 0.6). Recently, AC Her was observed to have a polar-aligned circumbinary disk. We perform hydrodynamic simulations to explore the impact of a polar-aligned disk on the eccentricity of a binary. For a binary system with central masses of 0.73 and 1.4 M ⊙, we find that a disk with a total mass of 0.1 M ⊙ can enhance the binary eccentricity from 0.2 to 0.7 within 5000 yr, or from 0.01 to 0.65 within 15,000 yr. Even if the disk mass is as low as 0.01 M ⊙, the binary eccentricity grows within our simulation time while the system remains stable. These eccentricity variations are associated with the variations of the inclination between the disk and the binary orbit due to von Zeipel–Kozai–Lidov oscillations. The oscillations eventually damp and leave the binary eccentricity at a high value. The numerical results are in good agreement with analytical estimates. In addition, we examine the AC Her system and find that the disk mass should be on the order of 10−3 M ⊙ for the disk to remain polar.

Source: The Astrophysical Journal

DOI: 10.3847/1538-4357/adcf1f

Authors: Shunquan Huang, Rebecca G. Martin, Stephen H. Lubow

Institutions: University of Nevada, Las Vegas, Space Telescope Science Institute

Language: English

Topic: Stellar, planetary, and galactic studies

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $4,499

Funder: National Aeronautics and Space Administration