Formation Scenario for Wide and Close Binary Systems

• DOI: 10.1086/529133
• Publication Date: 2008-04-04T15:46:15Z
• Authors: Masahiro N. Machida; Kohji Tomisaka; Tomoaki Matsumoto; Shu‐ichiro Inutsuka
• Keywords: Rotational energy; Fragmentation

Fragmentation and binary formation processes are studied using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud rotating in uniform magnetic field, we calculate the evolution from molecular core (n = 104 cm −3) to stellar (n≃ 1022 −3), where n denotes central density. We calculated 147 models different initial magnetic, rotational, thermal energies amplitudes of nonaxisymmetric perturbation. In collapsing cloud, fragmentation is mainly controlled by ratio rotational energy, regardless energy amplitude The rotation promotes fragmentation, while field delays or some cases suppresses through all phases evolution. results categorized into three types. When clouds have larger relation energies, occurs low-density phase (1012 −3≲ n≲ 1015 separations 3-300 AU. Fragments that appeared this expected evolve wide systems. On other hand, when only high-density (n≳ 1017 after experience significant reduction owing ohmic dissipation. appearing mutual ≲0.3 AU close No case sufficiently strong which single stars be born. Two types epoch reflect separations. might able observe bimodal distribution for radial separation protostar extremely young groups.