Solar flares are of great fundamental and practical interest. In some events the energy release might exceed 1026 J Tsurutani et al. (2003) and accompanying CME courses extremely severe magnetic storm. Because of very rare occurrence of such global flares a laboratory simulation appears to be an alternative that could provide experimental data necessary for physical understanding of this phenomenon and for verifying theoretical models. Flare involves processes on many widely varying spatial and time scales. In laboratory only some parts of the whole evolution could be attempted for simulation. The present work is focused on the last stage of eruption when a magnetic loop filled with heated plasma is ejected away from the Sun, either itself or pushed by an upcoming jet. The geometry of a flare loop suggests that a magnetic dipole and laser-produced plasma could be used to simulate this structure Nikitin & Ponomarenko (1995). In the present work similarity criteria that relate laboratory parameters to the natural phenomena, experimental set up and preliminary results are presented.

The magnetic field of the Sun and the plasma properties of its atmosphere, such as temperature, density and waves in the solar corona, determine the origin, energetics and evolution of the solar wind. The solar wind comes in three main kinds, as steady fast streams, variable slow flows and transient fast coronal mass ejections, with all being closely associated with the structure and activity of the coronal magnetic field that evolves on a multitude scales. This tutorial paper places emphasis on the observed and measured characteristics of the solar wind sources and their magnetic structure. The boundary conditions in the magnetically closed corona, in the transiently opening corona, and in the lastingly open corona (funnels and holes) will be discussed, and their influences on and consequences for the interplanetary solar wind be addressed. The resulting three-dimensional structure of the solar wind and its evolution over the solar cycle are also briefly discussed.

The dynamic process of magnetic flux emergence from the solar interior to the outer atmosphere may well be related with eruptive phenomena and intense events of the Solar activity. However, the physics of the emergence is not still well understood. Thus, we have performed 3D MHD simulations to study the rising motion of a twisted flux tube from the convection zone of the Sun and its interaction with a preexisting coronal magnetic field. The results show that the reconnection process depends criticaly on the initial relative orientation between the two magnetic flux systems into contact. On the other hand, the overal process of emergence depends mostly on the dynamics of the sub-photospheric plasma.

Solar coronal heating is a complex problem due to the variety of scales and physical phenomena involved, and intricacy of “boundary conditions”. Lattice models and self-organized criticality provide means to model phenomenologically some of the physics involved over a wide range of scales, and reproduce certain statistical features of solar flares. Furthermore, these models offer a basis for the study of Parker's hypothesis of coronal heating by nanoflares. We provide a short review of this approach pioneered by Lu & Hamilton (1991) and related more recent works involving lattice models.

Helioseismic holography is a technique used to image the sources of seismic disturbances observed at the solar surface. It has been used to detect acoustic emission, known as sun quakes, radiated from X-class solar flares. Since the seismic power emitted by the X-class flares has proved to be independent of the strength of the flare, we have undertaking a systematic search for seismic signatures from M-class solar flares, observed by SOHO-MDI.

We have detected significant acoustic emission from a few M-class solar flares. Preliminary results of the survey of M-type solar flares studied so far is available at: aira.astro.ro/~deanna/M.html.

The Kelvin-Helmholtz instability (KHI) could be a potential source for some of the Alfvénic fluctuations observed in the solar wind. The nonlinear evolution of KHI is examined in 2+1 dimensions in the context of magnetohydrodynamics. We derived a nonlinear Schródinger equation (NLSE) and we obtained soliton solutions of this 2+1 dimensions NLSE.

We have examined the effect of small- and large-scale structures in the solar wind on the topology and dynamics of the Earth's magnetosphere during magnetic storms. To do so, we ran global magnetohydrodynamic (MHD) simulations of a magnetic storm that occurred on 23-24 May 2000 by using upstream solar wind data from the ACE, IMP-8, and Wind spacecraft to run separate simulations of the global magnetosphere. This study suggests that the presence of small-scale structures in the solar wind can affect the global configuration of the magnetosphere.

The Rayleigh-Taylor instability (RTI) of a continuously stratified fluid has implications on the stability of solar and planetary interiors. A nonlinear stage of the two-dimensional RTI is studied by including various effects. By using the multiple scale method, we derived a nonlinear Schrödinger equation (NLSE) in 2+1 dimensions. We show the general soliton solutions of the NLSE and this allows to discuss their stability.

Kinematic solar dynamo models (KSDM) that use a solar like differential rotation profile usually fail to reproduce the latitudinal distribution of the toroidal magnetic fields. Usually, it is assumed that it is the larger radial shear present in the solar tachocline at higher latitudes that is the responsible for such results. We here consider variations in the shape and thickness of the tachocline and find that a better distribution of the toroidal fields is obtained when the thickness of the tachocline is $d_1=0.02R_{\odot}$, a smaller value than that conventionally used.

Using Big Bear Solar Observatory (BBSO) magnetograms and H${\alpha}$ images in a quiet region and a coronal hole, observed on 9 14 and 16, 2004, respectively, we have explored the magnetic flux emergence, disappearance and distribution in the two regions. The following results are obtained: (1) The evolution of magnetic flux in the quiet region is much faster than that in the coronal hole, as the flux appeared in the form of ephemeral regions in the quiet region is four times as large as that in the coronal hole, and the flux disappeared in the form of flux cancellation, three times as fast as in the coronal hole. (2) More magnetic elements with opposite polarities in the quiet region are connected by arch filaments. (3) The flux distribution of network and intranetwork (IN) elements is similar in both polarities in the quiet region. For network fields in the coronal hole, the number of negative elements is much more than that of positive elements. However for the IN fields, the number of positive elements is much more than that of negative elements. (4) In the coronal hole, the fraction of negative flux change obviously with different threshold flux density. 73% of the magnetic fields with flux density larger than 2 Gauss is negative polarity, and 95% of the magnetic fields is negative, if we only measure the fields with their flux density larger than 20 Gauss. These results display that in a coronal hole, stronger fields is occupied by one predominant polarity; however the majority of weaker fields, occupied by the other polarity.

Differential rotational rate of the magnetic field measured in the photosphere was calculated and its temporal dependence was studied using two independent methods. It was found that the rotational rate has a character of torsional waves running to the equator with 11 year periodicity. At high latitudes the rotation is getting slower during minimum of activity when the field measured there is stronger.

Based upon the similar time profiles of the hard x-ray and microwave emissions on 21 April 2002 flare-CME event, we argue that: (1) in the impulsive phase of the flare, the fast loop-loop reconnection triggered the quasi periodic magnetic energy release and particle acceleration with duration of the order of minute, (2) in the extended phase of the flare (01:40-01:50UT), the quasi period reconnection in current sheet produced the impulsive energetic electrons injection and modulated the microwave emissions with duration of 10-30 s, (3) the current driven instability enhances the magnetic energy releasing rate and scatters the energetic electrons, which may be used to explain the power index of the hard X-ray and microwave emissions.

Five series of coronal images have been obtained by V.Kulijanishvili during the total solar eclipse of the June 21, 2001, in Zambia, Lusaka. A photographic mirror-lens coronagraph-polarimeter (D=100 mm, F=1000 mm) was used. The absolute brightness, polarization and direction of polarization of the inner corona were measured. Standard techniques are used for the separation of the F- and K-coronas and for determination of coronal electron densities and temperatures. The background skylight polarization and intensity are calculated.

Total solar eclipses observed on the long baseline allow to obtain the pictures of white-light solar corona with the long temporal distance. New mathematical methods of coronal picture processing allow visualization of very faint coronal structures and enable to compare their position in corona with very high accuracy. We can detect the moving of these faint structures by comparing of pictures obtained on the different places during the same total solar eclipse. Some techniques and results are described in this paper.

Understanding the mechanism that causes the emergence of magnetic flux from the solar interior to the atmosphere, the drastic changes in the properties of the matter and magnetic fields along the rise and the interplay of dynamic and resistive phenomena that shape the emerged regions is one of the major open tasks in solar physics. Important advances are being made both in the theoretical modelling and in the observation of the emergence events. This review concentrates on recent advances through 3D numerical experiments carried out with massively parallel MHD and radiative transfer codes.

We present results of our study of dependence of planetary geomagnetic activity from geometric factors in geoeffective parameters taking into account orientation of the geomagnetic moment M relative to the vectors of the Interplanetary Magnetic Field (IMF) and electric field of the solar wind E during annual and daily motions of the Earth. We take as our data base space measurements of the IMF and solar wind velocity at the Earth's orbit for 1964-1998 and Kp, Dst indices. Variations of the geometric factors determined by mutual orientation of the vectors E and M can explain 50% of observed variations of Kp and 75% of Dst. We show that geomagnetic activity can reach very high levels of geomagnetic activity Kp = 8 for invariable values of the solar wind electric field by changing only geometric factors.

A class of exact analytic solutions to the Grad-Shafranov equation (GSE), in cylindrical geometry under assumption of axial symmetry is obtained. For this configuration all the physical quantities are invariant under rotations about a fixed direction, which we take it to be the direction Oz of a cylindrical polar coordinate system $(r, \theta, z)$. The obtained solutions can be employed to describe isothermal magnetostatic atmosphere.

This is a brief review of the quiescent large scale visible corona with an emphasis on the origin, structure and role of streamers in the solar wind. The review is mostly based on results from the last 10 years of the SOHO mission and the goal is to provide a coherent picture of what is known about streamers at the end of the current cycle.

The solar wind is considered as a steady fully ionized hydrogen plasma flow, with rotational symmetry. The Parker-spiral type magnetic field specifies the dependence of the flow speed on the radial distance and meridional angle if the plasma is assumed to be quasi-neutral and currentless. A two-particle kinetic model of the collisionless rotationally symmetrical plasma flow in a magnetic field is formulated and applied to estimate the flux and density of the solar wind. The obtained theoretical results are compared to the observational data.

A major problem for predicting the onset of Solar Proton Events is the detection of the magnetic connection between the flare and the earth. If there is a magnetic connection, the particles accelerated by a large solar event may impact the earth and produce the onset of a solar energetic proton event. Current physical models cannot predict the onset of a SPE mainly because of the chaotic conditions within the IMF structure. Kiplinger (1995) reported a high correlation between the existence of 10 MeV protons at Earth and a characteristic pattern of X-ray spectral evolution for several associated flares. We propose a practical approach that tries to detect the time intervals of this correlation. Our assumption is that a high correlation betwewn X-ray and protons at Earth is an important symptom of a magnetic connection and may help to prevent Solar Proton Events.