2018/06/13 by Kristin Lund, Ian Bonnell, I. A. Bonnell · 17 citations
Physics and Astronomy · #Accretion (finance) #Angular momentum #Angular momentum coupling #Astro and Planetary Science #Astrophysics #Astrophysics and Star Formation Studies #Binary number #Binary star #Binary system #Classical mechanics #Intermediate polar #Low Mass #Mass ratio #Neutron star #Physics #Specific relative angular momentum #Stars #Stellar, planetary, and galactic studies #Total angular momentum quantum number #White dwarf #X-ray binary #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1093/mnras/sty1584
published in Monthly Notices of the Royal Astronomical Society 479(2), 2235-2242 (Oxford University Press) · 9 pages, 5 figures, 1 table, accepted for publication in MNRAS
openalex publication_date 2018/06/13 · arxiv created 2018/06/19 · arxiv updated 2018/06/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We develop a semi-analytic model to investigate how accretion on to wide low-mass binary stars can result in a close high-mass binary system. The key ingredient is to allow mass accretion while limiting the gain in angular momentum. We envision this process as being regulated by an external magnetic field during infall. Molecular clouds are made to collapse spherically with material either accreting on to the stars or settling in a disc. Our aim is to determine what initial conditions are needed for the resulting binary to be both massive and close. Whether material accretes, and what happens to the binary separation as a result, depends on the relative size of its specific angular momentum, compared to the specific angular momentum of the binary. When we add a magnetic field we are introducing a torque to the system that is capable of stripping the molecular cloud of some of its angular momentum, and consequently easing the formation of high-mass binaries. Our results suggest that clouds in excess of 1000 M⊙ and radii of 0.5 pc or larger, can easily form binary systems with masses in excess of 25 M⊙ and separations of order 10 R⊙ with magnetic fields of order 100 |μ|G (mass-to-flux ratios of order five).