Open AccessFirst MHD simulation of collapse and fragmentation of magnetized molecular cloud cores
Author(s) -
Machida Masahiro N.,
Tomisaka Kohji,
Matsumoto Tomoaki
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.07402.x
Subject(s) - physics , magnetohydrodynamics , adiabatic process , hydrostatic equilibrium , rotational symmetry , molecular cloud , magnetic field , mechanics , astrophysics , outflow , fragmentation (computing) , star formation , astronomy , stars , quantum mechanics , meteorology , computer science , thermodynamics , operating system
This is the first paper about fragmentation and mass outflow in molecular clouds by using three‐dimensional magnetohydrodynamical (MHD) nested‐grid simulations. The binary star formation process is studied, paying particular attention to the fragmentation of a rotating magnetized molecular cloud. We assume an isothermal rotating and magnetized cylindrical cloud in hydrostatic balance. Non‐axisymmetric as well as axisymmetric perturbations are added to the initial state and the subsequent evolutions are studied. The evolution is characterized by three parameters: the amplitude of the non‐axisymmetric perturbations, the rotation speed and the magnetic field strength. As a result, it is found that non‐axisymmetry hardly evolves in the early phase, but begins to grow after the gas contracts and forms a thin disc. Disc formation is strongly promoted by the rotation speed and the magnetic field strength. There are two types of fragmentation: that from a ring and that from a bar. Thin adiabatic cores fragment if their thickness is less than 1/4 of the radius. For the fragments to survive, they should be formed in a heavily elongated barred core or a flat round disc. In the models showing fragmentation, outflows from respective fragments are found as well as those driven by the rotating bar or the disc.