The First Two Thousand Years of Star Formation

Masahiro N. Machida, Shantanu Basu

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Starting from a prestellar core with a size of 1.2 ×104 au, we calculate the evolution of a gravitationally collapsing core until ∼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 ×10-3 au. Following protostar formation, a rotationally supported disk is formed. Although the disk size is as small as ∼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 ∼100 . The jet opening angle widens with time at its base, while the jet keeps a very good collimation on a 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.

Original languageEnglish
Article number149
JournalAstrophysical Journal
Volume876
Issue number2
DOIs
Publication statusPublished - May 10 2019

Fingerprint

protostars
star formation
angular momentum
accretion
magnetic field
magnetohydrodynamics
torque
simulation
gravitational instability
cavity
spatial resolution
magnetohydrodynamic simulation
outflow
magnetic effects
neutral gases
collimation
bows
magnetic fields
ejection
low speed

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

The First Two Thousand Years of Star Formation. / Machida, Masahiro N.; Basu, Shantanu.

In: Astrophysical Journal, Vol. 876, No. 2, 149, 10.05.2019.

Research output: Contribution to journalArticle

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