SIMBAD references

2014ApJ...780...40B - Astrophys. J., 780, 40 (2014/January-1)

Non-ideal magnetohydrodynamic simulations of the two-stage fragmentation model for cluster formation.

BAILEY N.D. and BASU S.

Abstract (from CDS):

We model molecular cloud fragmentation with thin-disk, non-ideal magnetohydrodynamic simulations that include ambipolar diffusion and partial ionization that transitions from primarily ultraviolet-dominated to cosmic-ray-dominated regimes. These simulations are used to determine the conditions required for star clusters to form through a two-stage fragmentation scenario. Recent linear analyses have shown that the fragmentation length scales and timescales can undergo a dramatic drop across the column density boundary that separates the ultraviolet- and cosmic-ray-dominated ionization regimes. As found in earlier studies, the absence of an ionization drop and regular perturbations leads to a single-stage fragmentation on pc scales in transcritical clouds, so that the nonlinear evolution yields the same fragment sizes as predicted by linear theory. However, we find that a combination of initial transcritical mass-to-flux ratio, evolution through a column density regime in which the ionization drop takes place, and regular small perturbations to the mass-to-flux ratio is sufficient to cause a second stage of fragmentation during the nonlinear evolution. Cores of size ∼0.1 pc are formed within an initial fragment of ∼pc size. Regular perturbations to the mass-to-flux ratio also accelerate the onset of runaway collapse.

Abstract Copyright:

Journal keyword(s): diffusion - ISM: clouds - ISM: magnetic fields - magnetohydrodynamics, MHD - stars: formation

Simbad objects: 2

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2019.11.13-11:59:15

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