Star Formation and the Hall Effect

  title={Star Formation and the Hall Effect},
  author={Mark Wardle},
  journal={Astrophysics and Space Science},
  • M. Wardle
  • Published 4 July 2003
  • Physics
  • Astrophysics and Space Science
The breakdown of flux-freezing in molecular clouds and protostellar discs is usually approximated by ambipolar diffusion at low densities or by resistive diffusion at high densities. Here an intermediate regime is discussed in which the Hall term in the conductivity tensor is significant, and the vector evolution of the magnetic field, and therefore the evolution of the system under consideration is dramatically altered. Calculations of charged particle abundances in dense gas in molecular… 
The Hall effect in star formation
Magnetic fields play an important role in star formation by regulating the removal of angular momentum from collapsing molecular cloud cores. Hall diffusion is known to be important to the magnetic
Low-Mass Star Formation: From Molecular Cloud Cores to Protostars and Protoplanetary Disks
This review describes realistic evolution of magnetic field and rotation of the protostars, dynamics of outflows and jets, and the formation and evolution of protoplanetary disks. Recent advances in
Star Formation and the Hall Effect
Magnetic fields play an important role in star formation by regulating the removal of angular momentum from collapsing molecular cloud cores. Hall diffusion is known to be important to the magnetic
Numerical simulation of the Hall effect in magnetized accretion disks with the Pluto code
We investigate the Hall effect in a standard magnetized accretion disk which is accompanied by dissipation due to viscosity and magnetic resistivity. By considering an initial magnetic field, using
Magnetorotational instability in protoplanetary discs
We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionized, stratified accretion discs. The magnetic field is initially vertical and dust
The Kelvin–Helmholtz instability in weakly ionized plasmas: ambipolar-dominated and Hall-dominated flows
The Kelvin–Helmholtz instability is well known to be capable of converting well-ordered flows into more disordered, even turbulent, flows. As such it could represent a path by which the energy in,
Thermal instability in ionized plasma
We study the magneto-thermal instability in ionized plasmas including the effects of Ohmic, ambipolar and Hall diffusion. The magnetic field in the single-fluid approximation does not allow for
Nonideal Magnetohydrodynamic Turbulent Decay in Molecular Clouds
It is well known that nonideal magnetohydrodynamic (MHD) effects are important in the dynamics of molecular clouds: both ambipolar diffusion and possibly the Hall effect have been identified as
Angular momentum transport in protostellar discs
Angular momentum transport in protostellar discs can take place either radially, through turbulence induced by the magnetorotational instability (MRI), or vertically, through the torque exerted by a
Multifluid Magnetohydrodynamic Turbulent Decay
It is generally believed that turbulence has a significant impact on the dynamics and evolution of molecular clouds and the star formation that occurs within them. Non-ideal magnetohydrodynamic (MHD)


A Powerful Local Shear Instability in Weakly Magnetized Disks. II. Nonlinear Evolution
We consider the dynamical evolution of an accretion disk undergoing Keplerian shear flow in the presence of a weak magnetic field. A linear perturbation analysis presented in a companion paper shows
Magnetic flux loss from interstellar clouds with various grain-size distributions
The densities of charged particles and the dissipation of magnetic fields in interstellar clouds shielded from UV radiation and having densities between 1000 and 10 to the 13th/cu cm are
The Balbus-Hawley instability in weakly ionized discs
ABSTRA C T MHD in protostellar discs is modified by the Hall current when the ambipolar diffusion approximation breaks down. Here I examine the Balbus‐Hawley (magnetorotational) instability of a
Linear analysis of the Hall effect in protostellar disks
The effects of Hall electromotive forces (HEMFs) on the linear stability of protostellar disks are examined. Earlier work on this topic focused on axial field and perturbation wavenumber geometry.
The conductivity of dense molecular gas
We evaluate the conductivity tensor for molecular gas at densities ranging from 104 to 1015 cm-3 for a variety of grain models. The Hall contribution to the conductivity has generally been neglected
X-Ray Ionization of the Disks of Young Stellar Objects
We have developed a Monte Carlo code for the transport of stellar X-rays in an axially symmetric disk. The code treats Compton scattering and photoelectric absorption and follows the X-rays until
Magnetic flux loss from interstellar clouds
Une etude des densites de differentes particules chargees dans l'equilibre ionisation-recombinaison et de la dissipation du champ magnetique dans les nuages interstellaires est realisee avec de