We examine the energetics of Coronal Mass Ejections (CMEs) with data from the LASCO coronagraphs on SOHO. The LASCO observations provide fairly direct measurements of the mass, velocity and dimensions of CMEs. Using these basic measurements, we determine the potential and kinetic energies and their evolution for several CMEs that exhibit a flux-rope morphology. Assuming flux conservation, we us...

Microwave emission from solar active regions at frequencies above 4 GHz is dominated by gyroresonance opacity in strong coronal magnetic elds, which allows us to use radio observations to measure coronal magnetic eld strengths. In this paper we demonstrate one powerful consequence of this fact: the ability to identify coronal currents from their signatures in microwave images. Speciically, we c...

In this paper, the dynamical contraction of magnetized clouds is studied from the run-away phase to the accretion phase throughout. Since the non-homologous gravitational contraction necessitates progressively ner spatial resolution, \nested grid technique" (Burger & Oliger 1984) is adopted. As a result, it is found that out ow driven by toroidal magnetic elds is occurred in the accretion phase...

We investigate thermodynamic properties of noninteracting charged bosons in the presence of externally applied electric and magnetic "elds. Using the semiclassical density of states, we obtain the condensate fraction, chemical potential, total energy, and speci"c heat of a system of "nite number of charged Bose particles. We conclude that Bose}Einstein condensation of the charged Bose gas occur...

A partial decrease of the convective energy by the magnetic field of a sunspot causes the temperature of the magnetized plasma to decrease and this leads to a magneto-hydrostatic equilibrium. Thus, we expect a strong relation between magnetic field strength of a sunspot and its temperature/brightness. Here, we investigate this relation in the umbra of the large sunspot in NOAA10930 using spectr...

We adopt an isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field for estimating magnetic energy and helicity spectra as well as current helicity spectra of individual active regions and the change of their spectral indices with the solar cycle. The departure of the spectral index of current helicity from 5/3 is analyzed, and it is found that it ...

We derive a first order linear differential equation describing the shape of the probability density function of magnetic field strengths in the quiet Sun (PDF). The modeling is very schematic. It considers convective motions which continuously supply and withdraw magnetic structures. In addition, a magnetic amplification mechanism increases the field strength up to a threshold that cannot be e...

Ca II H emission is a well-known indicator of magnetic activity in the Sun and other stars. It is also viewed as an important signature of chromospheric heating. However, the Ca II H line has not been used as a diagnostic of magnetic flux emergence from the solar interior. Here we report on Hinode observations of chromospheric Ca II H brightenings associated with a repeated, small-scale flux em...

The main result of this paper is to reduce the calculation of higher-order terms in the asymptotic expansions of the electric and magnetic elds at low frequencies to the solutions of certain canonical problems. We also provide a new and simple variational proof of the convergence of the electric and magnetic elds solutions of the scattering problem for the Maxwell equations as the frequency goe...

Magnetic fields play a dominant role in the atmospheres of the Sun and other Sun-like stars. Outside sunspot regions, the photosphere of the so-called quiet Sun contains myriads of small-scale magnetic concentrations, with strengths ranging from the detection limit of ∼1016 Mx up to ∼ Mx. The tireless motion of these magnetic 20 3 # 10 flux concentrations, along with the continual appearance an...