Year: 2025
Type: article
Abstract: Observations of hierarchical triple-star systems show that misalignments are common both between the angular momentum vector of the inner binary and the outer companion orbit, and between the outer binary orbit and a circumtriple gas disk. With analytic methods and n-body simulations, we explore the dynamics of circumtriple orbits around a misaligned hierarchical triple star. Circumtriple test-particle orbits nodally precess either about the outer binary angular momentum vector (circulating orbits) or about a stationary inclination that depends upon the binary properties (librating orbits). For a coplanar (or retrograde coplanar) triple star, the apsidal precession rate is maximal and the critical orbital radius outside of which all orbits are circulating is minimal. Polar alignment of a circumtriple gas disk requires nodal libration, and therefore it can be more likely if there is a large misalignment between the inner and outer binary orbits. There are two values of the mutual misalignment, i c and 180° − i c, for which the apsidal precession rate of the triple star is zero and polar alignment is possible at all orbital radii. For a circular inner binary orbit i c = 55°, and it changes with the eccentricity of the inner binary while being insensitive to other triple-star parameters.
Source: The Astrophysical Journal
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Awards: G1722272692, G4128978252, G5499027263
OpenAlex ID: W4409519711