We present spectral analysis methods suitable for diagnostics of flaring plasma from RESIK spectra. RESIK is the uncollimated bent crystal spectrometer aboard the Russian CORONAS-F solar mission. It collected many flare and active region spectra in the wavelength range 3.3 Å–6.1 Å, where strong emission lines of Si, S, Ar, and K are present. Based on a careful instrument calibration the absolute fluxes in the individual spectral lines have been obtained. These fluxes have been used for determination of a set of thermodynamic parameters characterizing the emitting plasma and for studies their time behavior during selected flares.

We present a brief description of new complex of space telescopes and spectrographs, TESIS, which will be placed aboard the CORONAS-PHOTON satellite. The complex is intended for high-resolution imaging observation of full Sun in the coronal spectral lines and in the spectral lines of the solar transition region. TESIS will be launched at the end of 2007 – early of 2008. About 25 % of the daily TESIS images will be free for use and for downloading from the TESIS data center that is planned to open 2 months before the TESIS launching at http://www.tesis.lebedev.ru

We review how the so-called flux-transport solar dynamos work and show that such models calibrate well with solar cycle observations, and simulate well the relative peaks of the past 8 cycles. This success provides a basis for forecasting a strong solar cycle 24. We also show that a previous forecast of the timing of onset of cycle 24 is being verified by recent sunspot area statistics and coronal structures.

We present the results of numerical simulations of 3D magnetic reconnection driven by photospheric footpoint motions. The model consists of two positive and two negative sources, which are placed on opposite boundaries of the cubic domain. Two different types of photospheric motions are then considered, namely rotating and twisting of the sources. These different footpoint motions result in a difference in the evolution of the magnetic skeleton and the location and efficiency of the energy build up. Both the dynamical evolution and the corresponding potential evolution of each system is investigated and a comparison is made between the energy storage and release that occurs at separators and separatrix surfaces.

The present work concerns the study of the great solar proton events during the solar cycle 23. For this purpose, the temporal behavior of six solar indices during these great events will be studied. These indices are the radio flux (10.7cm) intensity, the sunspot no., the sunspot area, the GEOS X-ray background flux intensity, and the intensity of the X-ray flares and optical flares.

The stability behaviour of the wave modes that propagate in the solar wind plasma is considered in the framework of the Hall-magnetohydrodynamics. The Hall-MHD theory extends the wave frequency limit up to or higher than the ion cyclotron frequency. Due to the different flow velocities of the adjacent media in the solar wind, a Kelvin–Helmholtz instability is naturally expected to arise. The behaviour of the wave modes due to this particular kind of instability is studied under solar wind conditions typical for 1 AU. This is a preliminary study on the stability problem in the solar wind flowing structures and it could be relevant for the interplanetary and space weather research.

An occulted flare occurred at about 06:07 UT on November 2, 2002. The RHESSI X-ray images show two separate parts. The lower part consists of a complete loop and the upper part a coronal source which well extends above the solar limb. The loop source shrank for about 4 minutes with a speed of $\sim$24 km s$^{-1}$ during the early impulsive phase and then expanded at $\sim$7 km s$^{-1}$, while the coronal source presented an upward motion at about 6 km s$^{-1}$. The temperature of the loop-top is always higher than that near the footpoints. The temperature of the loop increased with altitude, while that of the coronal source just showed opposite variation. These results indicate that the reconnection X-point of this flare is located in between the loop-top source and the coronal source.

We present a statistical investigation of shear motion of the EUV footpoints in two-ribbon solar flares, using the high spatial resolution data obtained in 1998–2005 by the Transition Region and Coronal Explorer (TRACE). In this study we have selected 50 well-observed X- and M- class two-ribbon flares. Our preliminary results are: a) 86% (43 out of 50) of these flares show shear change of footpoints and ribbon separation; b) there is no obvious ribbon separation in those 7 flares which have no shear change of the conjugate footpoints; c) in most events, the cessation of shear change is 0–2 minutes earlier than the end of the impulsive phase.

Using one-minute cadence vector magnetograms of BBSO, we analyze the temporal behavior of the derived vertical electric currents associated with two solar flares on July 26, 2002. One is an M1.0 flare occurred in AR10044, while the other is an M8.7 flare in the adjacent AR 10039. We find that the temporal behaviors of electric currents are very different. For the M1.0 flare, the current density drops rapidly near the flaring neutral line; while for the M8.7 flare, the current density rapidly increases.

We present preliminary results of the study of the photospheric physical conditions about 30 minutes before the 2N/M2 two-ribbon solar flare. The soft X-ray enhancement, $H_{\alpha}$ brightening and microwave bursts occured prior to the flare. We demonstrate the semiempirical models of the preflaring photosphere fot two kernels of the future flare. These models derived from the inversion reproduce the spectral observations in seven Fraunhofer lines. The models consist of two atmospheres: the magnetic flux tube and its nonmagnetic surroundings. The inferred models show strong changes of the photospheric physical conditions in the preflare phase. The preheating was found in the flux tube. Upward motions of the surrounding photospheric material were revealed. Significant discrepancies of the flux-tube temperature and density are found for two sites of the future flare. The inner kernel located near the filament was cooler in the photosphere than the outer kernel.

Large scale eruption events in the solar atmosphere can generate global waves, i.e. waves which propagate over distances comparable to the solar radius. In the low solar corona, global waves observed by SOHO/EIT, generated by coronal mass ejections or flares are usually referred to as EIT waves. Since EIT waves carry information about their environment, they can be used for diagnostics of, e.g. the local and global magnetic field. This contribution presents theoretical models for finding values of magnetic field in the quiet Sun and coronal loops, and explores the physical connection between local and global solar coronal events (e.g. flares and coronal loop oscillations).

Based on the concept that the CMEs are the results of coronal magnetic restructuring or reconfiguring, we analyze the December 18, 2000 event by using Nançay Radioheliograph (NRH) images and combining the multi-spatial scale observations. We investigated the onset, duration and position of the radio emissions in relation to EUV dimming and the inferred CME onset, with the purpose to estimate the spatial and temporal scales of the coronal restructuring, thus, to understand the physics of the initiation and development of the CME.

We explain the generation of the large-scale unipolar magnetic field regions (global magnetic regions) by the same dynamo action as for the generation of the sunspots and the polar faculae butterfly diagrams as given by Callebaut (2006). The previous global magnetic regions through meridional circulation now serve as the main seed fields (flux-transport dynamo for the global field regions), possibly supplemented by leftovers from the sunspots and some weak fields generated at the tachocline.

In this paper we have used the general theory of Arnold (1965,1966) and Vladimirov et al. (1997) to obtain sufficient conditions for linear stability of steady MHD flows of an ideal three-dimensional compressible gravitating flows.

Everybody understands what is meant by an eclipse: a body that covers another one. However, the general audience and the students in particular do not know exactly “What the relative positions of the Earth, the Sun and the Moon have to be in order for an eclipse to take place?”

You can read a newspaper or watch TV and observe that the information about an eclipse is not correct. In my country, it was stated, in a very important newspaper, that “the solar eclipse will take place tomorrow because there will be a Full Moon”.

Teaching this topic in schools or in educational sessions in observatories, it is a good idea to introduce a simple model that maintains the proportion between the diameters and distances of these three bodies. This contribution will introduce this model, showing their applications in the playgrounds of the school, for sunny days or in the classroom for cloudy days.

The last decade observations revealed the essential variations of energy balance take place in the pre-flare active regions at all atmospheric levels and they are caused by both evolution of AR and processes associated with flare activity. We present the multi-wavelength study of the solar flare jointly with the preceding event. The combined investigation is perspective for the mechanism understanding of the energy storage, trigger and release during the solar flares. A special attention was given to signatures of energetic particle beam effect on chromosphere according to H$\alpha$ and CaII K intensity changes. Combination of data from ground based instruments and space observatories (TRACE, MDI, RHESSI) will allow us to track processes taking place in a wide range of solar atmosphere layers - from the temperature minimum region to the corona. The obtained results are discussed.

Based on the neutron monitor counting rate profiles, soft X-ray emission from GOES, Yohkoh/HXT, RHESSI/HXT, ACE/SIS, and SOHO/LASCO CME catalog, the relationship between the onset time of solar cycle 23 Ground Level Enhancements(GLEs) and solar activity are analyzed. It was found that the correlation between the onset time of GLEs and flare maximum is better than that of the onset time of metric type II radio burst and CME. Average value of the ratio of Fe/O is about 2.65 times of coronal value in the range 30 – 40 MeV/n for all events. If considering the parent flare sites, the situation of proton acceleration in flares, and transport effect from flare sites (if it located in poorly-connected region) to well-connected region, several GLEs onset time are roughly at the peak time of the X-ray.

Utilizing SOHO/MDI data of two active regions (ARs 08398 & 10373), we identify and trace the whole lifetimes of 26 positive and 68 negative unipolar Moving Magnetic Features (MMFs). The statistical properties of several kinematic and magnetic quantities are studied.

We argue that millimeter continuum observations promise to be an important diagnostic of chromospheric dynamics and the appropriate wavelengths to look for dynamic signatures are in the range 0.8–5.0 mm. We have analyzed the millimeter intensity spectrum expected from the dynamic model of the solar non-magnetic atmosphere of Carlsson & Stein (1992, 1995, 1997, 2002, hereafter CS) together with the interferometric observations of the quiet Sun obtained at a wavelength of 3.5 mm with the Berkeley-Illinois-Maryland Array. Model radio emission at millimeter wavelengths is found to be extremely sensitive to dynamic processes in the chromosphere, if these are spatially and temporally resolved. The estimated millimeter brightness temperatures are time-dependent, following changes in the atmospheric parameters, and result in clear signatures of waves with a period of 180 s seen in the radio intensity as a function of time. At the same time, the interferometric observations of the internetwork regions reveal significant oscillations with amplitudes of 50–150 K in the frequency range 1.5–8 mHz. We give an estimate of the influence of the limited available spatial resolution of observations on the comparison with the predictions of dynamic models. We are able to establish a correspondence between the CS model predictions and the observational data if we assume that the horizontal coherence length of the oscillations is on the order of 1 arcsec.

Magnetic field topology at the CME source regions is considered to play a role in CME initiation processes. We use observational data and Potential Field Source Surface model to investigate the magnetic field topology over CME productive quiescent filaments. We found both bipolar topology and quadrupolar topology at CME source regions, but bipolar topology is more common overall and in each year. The total occurrence ratio between bipolar and quadrupolar topology is about 3:1 with our 80 events. On the rising phase of the solar cycle, there is mostly bipolar topology, but on the declining phase, there is a mixture of both bipolar and quadrupolar topology.