Related papers: Field linkage and magnetic helicity density
The ohmic decay of magnetic fields in the crusts of neutron stars is generally believed to be governed by Hall drift which leads to what is known as a Hall cascade. Here we show that helical and fractionally helical magnetic fields undergo…
We present the largest sample of high-mass star-forming regions observed using submillimetre imaging polarimetry. The data were taken using SCUBA in conjunction with the polarimeter on the JCMT in Hawaii. In total, 16 star forming regions…
Kinetic helicity is a fundamental characteristics of astrophysical turbulent flows. It is not only responsible for the generation of large-scale magnetic fields in the Sun, stars, and spiral galaxies, but it also affects turbulent diffusion…
Several sets of data show that small interstellar grains captured in interstellar magnetic fields draped over the heliosphere appear to polarize the light of nearby stars. The maximum polarization direction is offset in ecliptic longitude…
Direct measurements of magnetic fields in low-mass stars of spectral class M have become available during the last years. This contribution summarizes the data available on direct magnetic measurements in M dwarfs from Zeeman analysis in…
Magnetism is one of the most important forces on the interstellar medium (ISM), anisotropically regulating the structure and star formation that drive galactic evolution. Recent high dynamic range observations of diffuse gas and molecular…
Radio continuum and polarization observations of several nearby galaxies allowed to determine their vertical scaleheights, magnetic field strengths and large-scale magnetic field patterns. They all show a similar large-scale magnetic field…
A model of magnetic field structure is presented to help test the prevalence of flux freezing in star-forming clouds of various shapes, orientations, and degrees of central concentration, and to estimate their magnetic field strength. The…
We seek to obtain a picture of the interstellar magnetic field in the Galactic center region that is as clear and complete as possible. To that end, we review the observational knowledge that has built up over the past 25 years on…
The electromagnetic helicity of the free electromagnetic field and the static magnetic helicity are shown to be two different embodiments of the same physical quantity, the total helicity. The total helicity is the sum of two terms: a term…
We present a suite of models of the coherent magnetic field of the Galaxy (GMF) based on new divergence-free parametric functions describing the global structure of the field. The model parameters are fit to the latest full-sky Faraday…
We present a study of the line-of-sight magnetic fields in five large-diameter Galactic HII regions. Using the Faraday rotation of background polarized radio sources, as well as dust-corrected H-alpha surface brightness as a probe of…
Correlation analysis is obtained among Faraday rotation measure, HI column density, thermal and synchrotron radio brightness using archival all-sky maps of the Galaxy. A method is presented to calculate the magnetic strength and its…
Strong, globally-organized magnetic fields are found for a small fraction of O, B, and A stars. At the same time, many theoretical and indirect observational studies suggested ubiquitous presence of weak localized magnetic fields at the…
Helicity, a measure of the linkage of flux lines, has subtle and largely unknown effects upon dynamics. Both magnetic and hydrodynamic helicity are conserved for ideal systems and could suppress nonlinear dynamics. What actually happens is…
Linearly polarized emission from dust grains and molecular spectroscopy is an effective probe of the magnetic field topology in the interstellar medium and molecular clouds. The longstanding Davis-Chandrasekhar-Fermi (DCF) method and the…
By defining an appropriate field line helicity, we apply the powerful concept of magnetic helicity to the problem of global magnetic field evolution in the Sun's corona. As an ideal-magnetohydrodynamic invariant, the field line helicity is…
Stellar magnetic fields can be investigated using several, very complementary approaches. While conventional spectroscopy is capable of estimating the average magnetic strength of potentially complex field configurations thanks to its low…
We derive horizontal fluid motions on the solar surface over large areas covering the quiet-Sun magnetic network from local correlation tracking of convective granules imaged in continuum intensity and Doppler velocity by the Helioseismic…
One of the key problems in star formation research is to determine the role of magnetic fields. Starting from the atomic inter-cloud medium (ICM) which has density nH ~ 1 per cubic cm, gas must accumulate from a volume several hundred pc…