The First Two Thousand Years of Star Formation

Abstract

Starting from a prestellar core with a size of $1.2\times 10^4$ AU, we calculate the evolution of a gravitationally collapsing core until $\sim 2000$ yr after protostar formation using a three-dimensional resistive magnetohydrodynamic simulation, in which the protostar is resolved with a spatial resolution of $5.6\times 10^{-3}$ AU. Following protostar formation, a rotationally supported disk is formed. Although the disk size is as small as $\sim 2-4$ AU, it remains present until the end of the simulation. Since the magnetic field dissipates and the angular momentum is then not effectively transferred by magnetic effects, the disk surface density gradually increases and spiral arms develop due to gravitational instability. The disk angular momentum is then transferred mainly by gravitational torques, which induce an episodic mass accretion onto the central protostar. The episodic accretion causes a highly time-variable mass ejection (the high-velocity jet) near the disk inner edge, where the magnetic field is well coupled with the neutral gas. As the mass of the central protostar increases, the jet velocity gradually increases and exceeds $\sim 100$ km s${}^{-1}$. The jet opening angle widens with time at its base, while the jet keeps a very good collimation on the large scale. In addition, a low-velocity outflow is driven from the disk outer edge. A cavity-like structure, a bow shock and several knots, all of which are usually observed in star-forming regions, are produced in the outflowing region.

31 pages, 13 figures, Accepted for publication in ApJ

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Cited by in corpus (27)

• Zooming in on Individual Star Formation: Low- and High-mass Stars
• The Effect of Misalignment between Rotation Axis and Magnetic Field on Circumstellar Disk
• ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP) II. Survey overview: a first look at 1.3 mm continuum maps and molecular outflows
• Formation and evolution of protostellar accretion discs. II. From 3D simulation to a simple semi-analytic model of Class 0/I discs
• Formation and evolution of protostellar accretion discs. I. Angular-momentum budget, gravitational self-regulation, and numerical convergence
• FAUST II. Discovery of a Secondary Outflow in IRAS 15398-3359: Variability in Outflow Direction during the Earliest Stage of Star Formation?
• Giant protostellar flares: accretion-driven accumulation and reconnection-driven ejection of magnetic flux in protostars
• The impact of non-ideal magnetohydrodynamic processes on discs, outflows, counter-rotation and magnetic walls during the early stages of star formation
• Early evolution of disk, outflow, and magnetic field of young stellar objects: Impact of dust model
• Fundamental scales in the kinematic phase of the turbulent dynamo
• Non-ideal magnetohydrodynamics vs turbulence II: Which is the dominant process in stellar core formation?
• Crescent-Shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA
• On the origin of magnetic fields in stars II: The effect of numerical resolution
• Impact of dust size distribution including large dust grains on magnetic resistivity: an analytical approach
• Twin Jets and Close Binary Formation
• FERIA: Flat Envelope Model with Rotation and Infall under Angular Momentum Conservation
• The impact of episodic outflow feedback on stellar multiplicity and the star formation efficiency
• Revealing multiple nested molecular outflows with rotating signatures in HH270mms1-A with ALMA
• Complex structure of a proto-brown dwarf
• Dynamic role of dust in formation of molecular clouds
• First observations of warm and cold methanol in Class 0/I proto-brown dwarfs
• Protostellar Outflows: a window to the past
• Turn up the light: Radiative efficiency of protostars at birth
• Can High-velocity Protostellar Jets Help to Drive Low-velocity Outflow?
• Co-evolution of dust grains and protoplanetary disks II: structure and evolution of protoplanetary disks; an analytical approach
• Numerical Insights into Disk Accretion, Eccentricity, and Kinematics in the Class 0 phase
• Super-fast Rotation in the OMC 2/FIR 6b Jet