Astrophysical magnetic fields

Subsequently Ya.B. s colleagues and students substantially advanced both the general theory of magnetic field generation and its practical applications to the Sun, galaxies, and other astrophysical objects. 

In view of their importance in many astrophysical questions, massive stars have been the subject of much work devoted to their evolution and nucleosynthesis. In spite of this, much obviously remains to be done, particularly on various astrophysics aspects of both the pre-supernova and supernova stages of their evolution. Among the questions that still call for further progress, let us mention the proper description of the transport of matter or of rotation, and of the structural effects of magnetic fields or of various instabilities that can develop prior to an eventual explosion. Uncertainties in the rates of some nuclear reaction and of weak interaction processes certainly do not have to be forgotten. Multi-dimensional simulations, especially at the late pre-supernova phases, are clearly in need. 

Supernova events as well as pre-supernova stages of stars play important roles in cosmochemistry. However, a number of aspects of astrophysics of both pre-supernova and supernova stages of evolution of massive stars remain unclear, as emphasized by Marcel Arnould (this volume). A major challenge comes from the uncertainties in the rates of some nuclear reactions and of weak interaction processes. Multi-dimensional simulations, especially of the late presupernova phases, are expected to be particularly helpful to understand these processes. Similarly, considerable efforts are still required for successful simulations of supernova explosions based on less uncertain pre-supernova models. Here again, the multi-dimensional treatment of a variety of physical effects, including rotation, magnetic fields, instabilities of different origins, and the transport of neutrinos needs careful inclusion. 

Aurora Geomagnetism Ionosphere Magnetic Fields in Astrophysics Space Plasma Physics Solar Physics Solar System, Magnetic and Electrical Fields... 

In controlled fusion experiments, as well as in astrophysics, magnetized plasmas play a very important role. Plasmas are said to be magnetized if the plasma is immersed into an equilibrium external magnetic field. 

Stepanov R., Frick P., Shukurov A., Sokololf D.. Wavelet tomography of the Galactic magnetic field. I. The method Astronomy and Astrophysics. 2002 391 361-368. 

A straightforward application of Zeeman spectroscopy is a magnetic-field determination using atoms with a known magnetic moment, and one of Stark spectroscopy is a measurement of an electric field using atomic levels with predetermined polarizability. Such measurements are useful when field-measuring probes based on other principles are either unusable or difficult to apply as in the astrophysical environment or in a plasma. 

Faraday rotation also occurs in a free electron gas where the amount of rotation depends on the product of B and the electron density integrated along the path. This is a tool used in astrophysics for estimating the magnetic field on the sim, stars, and in the interstellar medium. It also provides a method of deterinming the electron density in the ionosphere. 

Faraday effect The rotation of the plane of polarization by a bifringent medium. Produced astrophysically by the differential response of electrons in a magnetic field to right- and left-handed circular polarization. 

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