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Full-Text Articles in Astrophysics and Astronomy

Nonideal Magnetohydrodynamic Turbulent Decay In Molecular Clouds, Turlough Downes, Stephen O'Sullivan Aug 2009

Nonideal Magnetohydrodynamic Turbulent Decay In Molecular Clouds, Turlough Downes, Stephen O'Sullivan

Articles

It is well known that non-ideal magnetohydrodynamic effects are important in the dynamics of molecular clouds: both ambipolar diffusion and possibly the Hall effect have been identified as significant. We present the results of a suite of simulations with a resolution of 512-cubed of turbulent decay in molecular clouds incorporating a simplified form of both ambipolar diffusion and the Hall effect simultaneously. The initial velocity field in the turbulence is varied from being super-Alfvénic and hypersonic, through to trans-Alfvénic but still supersonic.


The Transport Of Cosmic Rays In Self‐Excited Magnetic Turbulence, Brian Reville, Stephen O'Sullivan, Peter Duffy, John Kirk May 2008

The Transport Of Cosmic Rays In Self‐Excited Magnetic Turbulence, Brian Reville, Stephen O'Sullivan, Peter Duffy, John Kirk

Articles

The process of diffusive shock acceleration relies on the efficacy with which hydromagnetic waves can scatter charged particles in the precursor of a shock. The growth of self-generated waves is driven by both resonant and non-resonant processes. We perform high-resolution magnetohydrodynamic simulations of the non-resonant cosmic ray driven instability, in which the unstable waves are excited beyond the linear regime. In a snapshot of the resultant field, particle transport simulations are carried out. The use of a static snapshot of the field is reasonable given that the Larmor period for particles is typically very short relative to the instability growth …