alfvén waves dissipation is an extensively studied mechanism for the coronal heating problem. these waves can be generated by magnetic reconnection and propagated along the reconnected field lines. here, we study the generation of alfvén waves at the presence of both steady flow and sheared magnetic field in the longitudinally density stratified of solar spicules. the initial flow is assumed to...

In astrophysical situations, e.g. in the interstellar medium (ISM), neutrals can provide viscous damping on scales much larger than the magnetic diffusion scale. Through numerical simulations, we have found that the magnetic field can have a rich structure below the dissipation cutoff scale. This implies that magnetic fields in the ISM can have structures on scales much smaller than parsec scal...

Both observations and modeling of magnetic fields in the diffuse interstellar gas of spiral galaxies are well developed but the theory has been confronted with observations for only a handful of individual galaxies. There is now sufficient data to consider statistical properties of galactic magnetic fields. We have collected data from the literature on the magnetic fields and interstellar media...

We demonstrate that the combination of Zeeman, polarimetry, and ion-to-neutral molecular line width ratio measurements permits the determination of the magnitude and orientation of the magnetic field in the weakly ionized parts of molecular clouds. Zeeman measurements provide the strength of the magnetic field along the line of sight, polarimetry measurements give the field orientation in the p...

There are two existing avenues to interpreting the diffuse ISM: the theorist’s approach in which real data is interpreted numerically in the context of simulations, and the observer’s approach in which objects are found and categorized by eye. We are pioneering a middle way, following the fast-growing science of machine vision to extract shape information from complex maps of the diffuse Galact...

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 ...

The role of magnetic fields in the dynamical evolution of galaxies and of the interstellar medium (ISM) is not well understood, mainly because such fields are difficult to directly observe. Radio astronomy provides the best tools to measure magnetic fields: synchrotron radiation traces fields illuminated by cosmic-ray electrons, while Faraday rotation and Zeeman splitting allow us to detect fie...

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...

Polarimetric maps have been used for the characterization of the magnetic field in molecular clouds. However, it is difficult to determine the 3-dimensional properties of these regions from the projected maps. For that reason, numerical simulations can be used as benchmarks for polarimetric measurements, and eventually reveal more about the interplay of turbulence and the magnetic field lines. ...

We propose a plasma experiment to be used to investigate fundamental properties of astrophysical dynamos. The highly conducting, fast flowing plasma will allow experimenters to explore the high-magnetic-Reynolds-number regime. The plasma is confined using a ring-cusp strategy and subject to a toroidal differentially rotating outer boundary condition. As proof of principle, we present magnetohyd...