Accretion, Outflows, and Winds of Magnetized Stars

Many types of stars have strong magnetic fields that can dynamically influence the flow of circumstellar matter. In stars with accretion disks, the stellar magnetic field can truncate the inner disk and determine the paths that matter can take to flow onto the star. These paths are different in stars with different magnetospheres and periods of rotation. External field lines of the magnetosphere may inflate and produce favorable conditions for outflows from the disk-magnetosphere boundary. Outflows can be particularly strong in the propeller regime, wherein a star rotates more rapidly than the inner disk. Outflows may also form at the disk-magnetosphere boundary of slowly rotating stars, if the magnetosphere is compressed by the accreting matter. In isolated, strongly magnetized stars, the magnetic field can influence formation and/or propagation of stellar wind outflows. Winds from low-mass, solar-type stars may be either thermally or magnetically driven, while winds from massive, luminous O and B type stars are radiatively driven. In all of these cases, the magnetic field influences matter flow from the stars and determines many observational properties. In this chapter we review recent studies of accretion, outflows, and winds of magnetized stars with a focus on three main topics: (1) accretion onto magnetized stars; (2) outflows from the disk-magnetosphere boundary; and (3) winds from isolated massive magnetized stars. We show results obtained from global magnetohydrodynamic simulations and, in a number of cases compare global simulations with observations.Comment: 60 pages, 44 figure

The Discontinuous Solutions of a Multicomponent Filtration Equations.

Abstract: The work is devoted to research of strong and weak discontinuities of multicomponent filtration equations. It is shown that the velocities of weak discontinuities of concentrations are decisions of certain eigenvalues problem. The entropy condition for strong discontinuities is obtained.Note: Research direction:Mathematical problems and theory of numerical method

Approximate Solution of Riemann's Problem for Relativistic MHD Equations.

Abstract: This work is devoted to construction of approximate solution of Riemann's problem for equations of relativistic magnetohydrodynamics. Equations, which describe the dynamic of perfectly conducted plasma and electromagnetic field are shown in the form of Lichnerowicz. Riemann's problem are solved in acoustic approximation and analytical expressions for right null-vectors and magnitudes of all physical waves are obtained.Note: Research direction:Mathematical problems and theory of numerical method

A Numerical Method for Simulation of the Detonation Front Propagation.

Abstract: The computing algorithm for numerical integration of equations of gas dynamics with fronts of energy release is proposed. The mobile calculated grids are used, that permits to allocate mentioned fronts, being strong breakages of decision. The iterative procedure of decision of task about decay of breakage in combustible mix is described. Is considered, that the current arising thus contains the deflagration wave (breakage), driving with fixed speed concerning to substance.Note: Research direction:Mathematical modelling in actual problems of science and technic