We use the mean-eld dynamo equations to show that spatially and temporally incoherent uctuations in the helicity in mirror-symmetric turbulence in a shearing ow can generate a large scale, coherent magnetic eld. We illustrate this eeect with simulations of a few simple systems. For statistically homogeneous turbulence we nd that the dynamo growth rate is roughly ?2=3 eddy ?1=3 shear N ?1=3 eddy...

The ”reverse–dynamo” mechanism — the amplification/generation of fast plasma flows by micro scale (turbulent) magnetic fields via magneto–fluid coupling is recognized and explored. It is shown that macroscopic magnetic fields and flows are generated simultaneously and proportionately from microscopic fields and flows. The stronger the micro–scale driver, the stronger are the macro–scale product...

A comparative study of the geomagnetic and ionospheric data at equatorial and low-latitude stations in India over the 20 year period 1956±1975 is described. The reversal of the electric ®eld in the ionosphere over the magnetic equator during the midday hours indicated by the disappearance of the equatorial sporadic E region echoes on the ionograms is a rare phenomenon occurring on about 1% of t...

We describe an implicit prediction of the accretion disk models constructed by Wardle and Königl (1990) for the circumnuclear disk (CND) of gas and dust near the Galactic center: supersonic ambipolar diffusion, an essential dynamical ingredient of the Wardle-Königl disks, will cause the alignment of dust grains due to a process described by Roberge, Hanany, & Messinger (1995). We calculate synt...

We present a new model of molecular cloud cores that originate from filamentary clouds that are threaded by helical magnetic fields. Only modest toroidal fields are required to produce elongated cores, with intrinsic axis ratios in the range 0.1 < ∼ q < ∼ 0.9 and mean projected axis ratios in the range 0.3 < ∼ 〈p〉 < ∼ 1. Thus many of our models are in good agreement with the observed shapes of ...

We have calculated the cosmic ray (CR) acceleration at young remnants from Type Ia supernovae expanding into a uniform interstellar medium (ISM). Adopting quasi-parallel magnetic fields, gasdynamic equations and the diffusion convection equation for the particle distribution function are solved in a comoving spherical grid which expands with the shock. Bohm-type diffusion due to self-excited Al...

We report on Australia Telescope Compact Array observations in the direction of the young high magnetic-Ðeld pulsar J1119[6127. In the resulting images we identify a nonthermal radio shell of diameter 15@, which we classify as a previously uncataloged young supernova remnant, G292.2[0.5. This supernova remnant is positionally coincident with PSR J1119[6127, and we conclude that the two objects ...

We present the results of a λ20 cm VLA observation of the compact Galactic center radio source Sgr A. The scatter-broadened image is elongated in the East-West direction, with an axial ratio of 0.6±0.05 and a position angle of 87±3. A similar shape and orientation has been found previously at shorter wavelengths using VLBI and VLBA. Both the major and minor axes follow the λ law appropriate for...

In this paper we present calculations of period distribution for old accreting isolated neutron stars (INSs). At the age about few billions years low velocity INSs come to the stage of accretion. At that stage their period evolution is governed by magnetic braking and accreted angular momentum. Due to turbulence of the interstellar medium (ISM) accreted momentum can both accelerate and decelera...

We used magnetohydrodynamic (MHD) simulations of interstellar turbulence to study the probability distribution functions (PDFs) of increments of density, velocity, and magnetic field. We found that the PDFs are well described by a Tsallis distribution, following the same general trends found in solar wind and Electron MHD studies. We found that the PDFs of density are different in subsonic and ...