2009/01/01 by Masahiro N. Machida, Shu-ichiro Inutsuka, Shu‐ichiro Inutsuka +1
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Adiabatic process #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Core (optical fiber) #Field line #Hydrostatic equilibrium #Jet (fluid) #Magnetic field #Magnetohydrodynamics #Mechanics #Molecular Spectroscopy and Structure #Optics #Outflow #Physics #Protostar #RADIUS #Star formation #Stars #Velocity gradient #astro-ph.SR
paper · pdf · doi:10.1007/978-3-642-00576-3_48
To appear in the proceedings of the "Protostellar Jets in Context" conference held on the island of Rhodes, Greece (7-12 July 2008)
openalex publication_date 2009/01/01 · arxiv created 2009/07/20 · arxiv updated 2015/05/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate the driving mechanism of outflows and jets in star formation process using resistive MHD nested grid simulations. We found two distinct flows in the collapsing cloud core: Low-velocity outflows (sim 5 km/s) with a wide opening angle, driven from the first adiabatic core, and high-velocity jets (sim 50 km/s) with good collimation, driven from the protostar. High-velocity jets are enclosed by low-velocity outflow. The difference in the degree of collimation between the two flows is caused by the strength of the magnetic field and configuration of the magnetic field lines. The magnetic field around an adiabatic core is strong and has an hourglass configuration. Therefore, the low-velocity outflow from the adiabatic core are driven mainly by the magnetocentrifugal mechanism and guided by the hourglass-like field lines. In contrast, the magnetic field around the protostar is weak and has a straight configuration owing to Ohmic dissipation in the high-density gas region. Therefore, high-velocity jet from the protostar are driven mainly by the magnetic pressure gradient force and guided by straight field lines. Differing depth of the gravitational potential between the adiabatic core and the protostar cause the difference of the flow speed. Low-velocity outflows correspond to the observed molecular outflows, while high-velocity jets correspond to the observed optical jets. We suggest that the protostellar outflow and the jet are driven by different cores (the first adiabatic core and protostar), rather than that the outflow being entrained by the jet.