A wide variety of radio propagation and scattering phenomena observed when a radio source is occulted by the solar corona has formed the basis for probing the solar corona for over four decades. The purpose of this paper is to review the subject of transients — variations in the radio occultation measurements that appear different from those of the background solar wind. A major surprise in the...

We present a model of magnetohydrodynamic (MHD) turbulence in the extended solar corona that contains the effects of collisionless dissipation and anisotropic particle heating. Recent observations have shown that preferential heating and acceleration of positive ions occur in the first few solar radii of the high-speed solar wind. Measurements made by the Ultraviolet Coronagraph Spectrometer ab...

The “Middle Corona”, defined by recent consensus as the region spanning 1.5–6 solar radii (R ⊙ , heliocentric), is an important zone through which several structural and dynamic changes occur in coronal streamer regions. Among these a regime change from high density, closed magnetic field structures to open of much lower electron concentration. Along with this complex restructuring, forming slo...

We have performed the first fully three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulation of jet formation from a thin accretion disk around a Schwarzschild black hole with a free-falling corona. The initial simulation results show that a bipolar jet (velocity ∼ 0.3c) is created as shown by previous two-dimensional axisymmetric simulations with mirror symmetry at the equat...

The solar corona is a tenuous outer atmosphere of the Sun. Its million-degree temperature was discovered spectroscopically in the 1940s, but its origin has been debated since then without complete convergence. Currently there are two classes of models; the wave theory and the microflare/nanoflare theory. Both models have merits and disadvantages, but the essential issues are nearly pinned down....

It is well established now that the solar atmosphere, from photosphere to the corona and the solar wind is a highly structured medium. Satellite observations have confirmed the presence of steady flows. Here, we investigate the parallel propagation of magnetohydrodynamic (MHD) surface waves travelling along an ideal incompressible flowing plasma slab surrounded by flowing plasma environment in ...

The evolution of an initially stellar dipole type magnetosphere interacting with an accretion disk is investigated numerically using the ideal MHD ZEUS-3D code in the 2Daxisymmetry option. Depending mainly on the magnetic field strength, our simulations may last several thousands of Keplerian periods of the inner disk. A Keplerian disk is assumed as a boundary condition prescribing a mass inflo...