نتایج جستجو برای: ISM: Magnetic fields

تعداد نتایج: 541421  

Journal: :journal of sciences, islamic republic of iran 2011
p. davoudifar

cosmic rays (cr) travel at speeds essentially indistinguishable from the speed of light. however whilst travelling through magnetic fields, both regular and turbulent, they are delayed behind the light since they are usually charged particles and their paths are not linear. those delays can be so long that they are an impediment to correctly identifying sources which may be variable in time. fu...

Journal: :iranian journal of astronomy and astrophysics 2014
mohsen nejad-asghar hajar harati

magnetic fields play an important role in creating, driving, and in the evolution of outflows and jets from protostars and accretion disks. on the other hand, the temperature profile of the accretion disks may also affect the structure of the magnetic field and outflows. in this paper, we use the self-similar method in cylindrical coordinates to investigate the effect of the temperature profile...

Journal: :Proceedings of the International Astronomical Union 2007

2008
James M. Stone Eve C. Ostriker Charles F. Gammie

We report results of a three dimensional, high resolution (up to 512) numerical investigation of supersonic compressible magnetohydrodynamic turbulence. We consider both forced and decaying turbulence. The model parameters are appropriate to conditions found in Galactic molecular clouds. We find that the dissipation time of turbulence is of order the flow crossing time or smaller, even in the p...

2009
Dominik Wóltański Kacper Kowalik

We report first results of first global galactic-scale CR-MHD simulations of cosmicray-driven dynamo. We investigate the dynamics of magnetized interstellar medium (ISM), which is dynamically coupled with the cosmic-ray (CR) gas. We assume that exploding stars deposit small-scale, randomly oriented, dipolar magnetic fields into the differentially rotating ISM, together with a portion of cosmic ...

2008
Fabio De Colle

The dynamical effects of magnetic fields in models of radiative, Herbig-Haro (HH) jets have been studied in a number of papers. For example, magnetized, radiative jets from variable sources have been studied with axisymmetric and 3D numerical simulations. In this paper, we present an analytic model describing the effect of a toroidal magnetic field on the internal working surfaces that result f...

2004
M. Hanasz G. Kowal K. Otmianowska-Mazur

We present the first numerical model of the magnetohydrodynamical cosmic-ray (CR) driven dynamo of the type proposed by Parker (1992). The driving force of the amplification process comes from CRs injected into the galactic disk in randomly distributed spherical regions representing supernova remnants. The underlying disk is differentially rotating. An explicit resistivity is responsible for th...

2005
Hidekazu Hanayama Kohji Tomisaka

The evolution of supernova remnants (SNRs) is studied, with particular attention to the effect of magnetic fields with axisymmetric two-dimensional magnetohydrodynamical simulations. The evolution of magnetic SNRs is the same as non-magnetic ones in the adiabatic Sedov stage. After a thin shell is formed, the shell is driven by the pressure of the hot interior gas (bubble). Evolution in the pre...

2005
Swadesh M. Mahajan Nana L. Shatashvili

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...

Journal: :iranian journal of astronomy and astrophysics 2014
elham bazyar ali ajabshirizadeh zahra fazel jean-pierre rozelot

virial theorem is important for understanding stellar structures. it produces an interesting connection between magnetic and gravitational energies. using the general form of the virial theorem including the magnetic field (toroidal magnetic field), we may explain the solar dynamo model in relation to variations of the magnetic and gravitational energies. we emphasize the role of the gravitatio...

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