2017/06/02 by Andrei Tokovinin, Andreï Tokovinin · 2 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics #Astrophysics and Star Formation Studies #Circular orbit #Dissipative system #Distribution (mathematics) #Eccentricity (behavior) #Geometry #Mathematical analysis #Orbit (dynamics) #Orbital eccentricity #Orbital elements #Physics #Quantum mechanics #Stars #Stellar, planetary, and galactic studies #Triple system #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/aa7746
Accepted by ApJ. 7 pages, 6 figures, 2 online-only tables
arxiv created 2017/06/02 · openalex publication_date 2017/07/27 · arxiv updated 2017/08/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Abstract The statistics of the angle Φ between orbital angular momenta in hierarchical triple systems with known inner visual or astrometric orbits are studied. A correlation between apparent revolution directions proves the partial orbit alignment known from earlier works. The alignment is strong in triples with outer projected separation less than ∼50 au, where the average Φ is about . In contrast, outer orbits wider than 1000 au are not aligned with the inner orbits. It is established that the orbit alignment decreases with the increasing mass of the primary component. The average eccentricity of inner orbits in well-aligned triples is smaller than in randomly aligned ones. These findings highlight the role of dissipative interactions with gas in defining the orbital architecture of low-mass triple systems. On the other hand, chaotic dynamics apparently played a role in shaping more massive hierarchies. The analysis of projected configurations and triples with known inner and outer orbits indicates that the distribution of Φ is likely bimodal, where 80% of triples have and the remaining ones are randomly aligned.