The properties of the magnetic field in the coronal holes (CH) were considered during 1996-2002. The daily observations from the Kitt Peak observatory in the line HeI 10830Å were compiled. The measurement of the magnetic fields in the CH was carried out by comparing the data obtained from the Kitt Peak telescope and the magnetograms of SOHO/MDI. The dependence between the brightness of CH from intensity of the magnetic field and distributions of CH depending from the magnetic field and latitude were presented for minimum and maximum of the cycle. The latitude and the unipolarity degree of the magnetic field that influence on the brightness of the CH were examined. It was shown that the average magnetic field was 1-2G, the unipolarity degree of the magnetic field was 0.1-0.3 and brightness of the coronal holes increases with the average magnetic field. The latitude-time distributions of CH for different polarity were obtained.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The main observable components of coronal mass ejections (CMEs) are the core, cavity and the frontal structure (FS), which is the leading edge of the visible CME. The core of a CME is associated with an eruptive filament whose motion can be followed just from the solar surface. As a rule, the FS is visible in scattered white light (SOHO/LASCO) far from the CME origination site. In few cases in near-the-limb events, the FS was detected closer to the solar surface. However, it appears not possible to detect any manifestations of the FS in a reasonable proximity of the pre-eruptive filament localized on the sun far from the limb. The identification of the FS remains unclear. We propose a method to estimate parameters of the initial volume of a CME based on the comparison of measured height-time plots of its structural components with a self-similar solution of MHD equations describing the expansion of a CME.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The spectra of the MnI 539.47 nm spectral line were observed in three different sunspots of the NOAA 0431 active region. Perpendicularly to the dispersion axis, the spectra were divided into several strips that covers the quiet photosphere, penumbra and the umbra of the appropriate sunspot. The manganese spectral line parameters variation along the spectrograph slit were determined and analyzed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Figure 1 shows the horizontal velocity pattern of photospheric features in the main part of active region NOAA 9077 on 2000 July 12 – 15, where the horizontal velocity vectors are overlapped by white light images (left) and contours represent $G=-2{\bf U}\cdot {\bf A_p}B_n$ (injective rate of magnetic helicity) inferred from the horizontal velocity vectors and longitudinal magnetic field (right). The black (white) contours with white (black) areas mark the positive (negative) change rate of magnetic helicity of $\pm$5, 20, 50, 100, 180, 300 ($\times 10^{13}G^2m^2s^{-1}$). The arrows overlapped by $G$ mark the transverse magnetic field.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In the past 10 years, observations from space have generated a genuine revolution in our understanding of the Sun. Its interior is now “observed” down to a few % of the solar radius, its internal dynamics, its rotation and the large scale flows that are found to exist under its “surface” are studied continuously for over nearly a complete solar cycle. The mechanisms that underlie solar activity are better understood as well as their effects on the heliosphere and on the planets of the Solar System, in particular on the Earth.

However, there are still opened questions that deserve to be answered through a new generation of space instruments, requiring the best experts in the world and an extended fleet of space missions that no single country is able today to undertake alone. In this context, the International Living with a Star programme is a key element that must be pursued with full strength. At the same time, new missions that are not part of that programme should begin to be studied. They will provide the ultimate resolution and accuracy that are necessary to go a step further in the knowledge of the Sun and of its effects on our planet.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Modern solar telescope design in the EUV to x-ray range is now capable of producing large images in multiple channels at rapid cadences, with high spatial and temperature resolution. We discuss reconstruction of differential emission measures for solar coronal plasma using two state-of-the-art instruments: the X-Ray Telescope on Solar-B, and the Atmospheric Imaging Assembly on the Solar Dynamics Observatory. We discuss the relative merits of iteration and direct inversion methods for determining DEM($T$). We also consider strategies for automating and visualizing DEM maps, given the high data rates that these instruments will produce. We touch on the scientific potential of high-cadence, spatially resolved DEM data products.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

This paper reviews some recent results obtained from multi-wavelength studies that extend from white light to radio. Special emphasis is given to radio observations, which can be used to determine emission mechanisms and to trace electron propagation paths and plasma motions. Multi-wavelength comparisons have been found to be essential when analysing flare- and CME-related eruptions, but significant results have also been obtained in ‘quiet’ Sun studies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Three approaches for coronal magnetic loops on the Sun and the stars are considered: (i) loop as MHD-resonator, (ii) loop as electric circuit, (iii) loop as a magnetic mirror trap.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Soft X-ray observations by Yohkoh SXT have revealed that transient brightenings of small coronal loops frequently occur in active regions. Their estimated energy is $10^{24} \sim 10^{28}$ ergs and non-thermal behaviors may be observed in the large member of the brightenings. They are considered as soft X-ray signatures of microflares observed in hard X-rays. Lower coronal temperature plasma (1-2MK) produced by Yohkoh transient brightenings is simultaneously observed in EUV wavelengths by TRACE and SoHO EIT/CDS. Moreover, EUV observations have shown a lot of tinier transient brightenings without accompanying SXT transient brightenings. Coordinated observations with photospheric observations show that the location of Yohkoh transient brightenings is well localized in active regions, i.e., in emerging flux regions, around well-developed sunspots, and in the coronal bundles connecting the leading plage to the following plage regions. In some Yohkoh events, small-scale emergence of magnetic flux is well associated with their occurrence, suggesting that emerging flux plays a key role in triggering transient energy release in the corona. This paper reviews multi-wavelength observations coordinated with Yohkoh SXT observations for investigating the nature of SXT transient brightenings (SXR microflares) and their associated emerging flux. Finally, Solar-B space observatory is briefly introduced as a next powerful tool for multi-wavelength investigations.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Magnetic coupling relates the energy sources below the photosphere to the structure and dynamics of the chromosphere and corona of the Sun. Multi-wavelength investigations of the solar activity provides the information needed to understand the acting physical mechanisms. Descriptions of magnetic coupling often start with force-free mathematical extrapolations of the photospheric magnetic field. Observations have revealed, however, perpendicular electric current sheets, reconnection and other locally non-force-free structures in chromosphere and corona. Obviously, the solar magnetic coupling includes dynamic forcing due to photospheric plasma motion. We developed a model which though it starts with force-free extrapolated observed photospheric magnetic field additionally takes into account the energy input due to the chromospheric neutral gas and plasma motion. We demonstrate the abilities of our model by applying it to SoHO multi-wavelength observations of an EUV bright point (BP).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The solar results from CORONAS-F satellite have been reviewed. The observations with the DIFOS multi-channel photometer in a broad spectral range from 350 to 1500 nm have allowed to determine the dependence of the relative amplitudes of p-modes of the global solar oscillations on the wavelength. The EUV observations in SPIRIT experiment have enabled the study of various manifestations of solar activity and high-temperature events on the Sun. The data from the flare instruments-gamma spectrometer HELICON, flare spectrometer IRIS, amplitude-time spectrometer AVS-F, and X-ray spectrometer RPS-1 have been used to analyze the hard emission from solar flares and to carry out the diagnostics of the solar flare plasma. The Solar Cosmic Ray Complex has investigated the solar flare effects in the Earth's environment. The UV emission variations during solar flares in the vicinity of the 120-nm wavelengh have been recorded and the relative variation amplitude has been determined.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Moreton waves are flare-associated waves observed to propagate across the solar disk in H$\alpha$, especially in the wing of H$\alpha$. The Flare Monitoring Telescope at Hida Observatory of Kyoto University observed 12 events associated with flare waves (i.e., Moreton waves and/or filament oscillations) in H$\alpha$ from 1997 to 2002. We review our studies of Moreton waves based on these observations;

1. relation between EIT wave and Moreton wave (Eto et al. 2002),

2. simultaneous observation with X-ray wave (Narukage et al. 2002),

3. three dimensional structure of flare-associated wave (Narukage et al. 2004),

4. relation between Moreton waves and filament eruptions.

The quantitative relation between the brightness of the coronal green line 530.5 nm Fe XIV and the magnetic field strength is considered over the 1977-2001 period. It is found that the correlation coefficients between these two parameters calculated separately inside and outside the sunspot formation zone $\pm 30^{\circ}$ have cyclic variation and occur in anti-phase. This suggests different mechanisms of formation of the corona in the fields of small, medium, and large scales. These results can be used for quantitative verification of the corona heating models.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Formation and evolution of coronal holes of different type are investigated. Occurrence and evolution of coronal holes in active regions are connected to the processes occurring in these active regions in particular with flares and CMEs. Coronal holes which are not connected to active regions reflect distribution of large-scale solar magnetic fields and their dynamics determined by global solar magnetic field structure changes.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In Eselevich V. and M. Solar Phys. 195, 319, 2000 is shown that in brightness rays of the streamer belt from time to time there exist additional plasma streams of enhanced density moves antisunward and occupies a separate ray. The duration of additional streams can range from a few hours to several days. For that reason, some of them may be categorized as sporadic SW streams and the others as quasi-stationary SW streams. Preliminary investigations showed that the leading edge of such streams can be extremely small in width. The purpose of this paper is to verify the conclusions about the existence of additional plasma streams with steep fronts in streamer belt rays, based on analyzing the calibrated data from LASCO/SOHO C2 and C3.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Halo CMEs represent the three-dimensional moving structures, located out of the plane of the sky (Howard et al. 1982, St. Cyr et al. 2000). At that one halo CMEs move toward the Earth (frontside Halo CMEs), other - away from the Earth, St. Cyr. Frontside halo CMEs play the special role in phenomena, associated with space weather, Crosby (2001). The largest geomagnetic storms are caused by influencing such CMEs on the magnetosphere of the Earth (Webb et al. 2000, St. Cyr et al. 2000). Using the images of halo CMEs in the field of view of a coronagraph it is possible to determine only their apparent characteristics in the plane of the sky. But in this case it is difficult define its important parameters such as directions of movement, angular sizes in various sections of CME, position of the CME “center” or of its front, velocities of CME elements along directions which are not located in the plane of the sky. Without these parameters it is impossible to find the mass of CME, it's kinetic and potential energy. In the present work the methods are offered and approved allowing the estimation of the listed above halo CMEs parameters, which are determined with difficulty.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Coronal holes (CHs) are large-scale regions of the corona with decreased density of material and temperatures. CHs are characterized by predominantly an open configuration of magnetic field lines. CHs are observed as regions of corona with decreased emission in soft X-rays, and appear simultaneously in different emission lines in distinct regions of solar atmosphere, Zirin (1988). CHs are known to be the source of the fast quasi-stationary solar wind (Nolte et al. 1976). At the same time answers to key questions which are related to the originating (the birth) of coronal holes till now are not obtained. It is known a little works in which the birth of CHs were investigated (Solodina et al. 1977; Bohlin & Sheeley 1978; Watari et al. 1995). The objective of this paper is to study the birth of non-polar CHs. This paper continues our paper Fainshtein et al. (2002), in which one the birth of coronal holes was studied.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

This paper is devoted to the investigation of the synchronous enhancements of the solar source fluxes according to the RATAN-600 Southern Sector observations at the 1.92 cm, 2.24 cm, 2.74 cm, and 3.21 cm radio waves. The observations were carried out on 11.09.01 from 8:30 UT to 10:30 UT every 8 min. We use the term “synchronous bursts” or “synchronous brightenings” instead of the “sympathetic bursts” as the time resolution of the RATAN - 600 is not high. The solar source brightenings are synchronous if they are registered in 2 - 2.5 min time lag, i.e. in the time interval of passage of the Sun through the central part of the main lobe of the antenna power pattern. The high flux sensitivity of the radio telescope - radiometer system was 0.005 s.f.u. The solar sources were identified with the active regions: AR 9610, AR 9608, AR 9606, AR 9616, AR 9617, which widely separated from each other (up to $10^{6}$ km). According to our observations, the synchronous enhancements were observed at the moments of the soft X ray brightenings and X ray bursts (Figure 1a). The temporal variations of the relative fluxes of the solar sources $F/F_{0}$ were compared to the $X$-ray (GOES 8,10; $H_{\alpha}$ - flares and to the radio bursts at 9100 MHz, $F_{0}$ - the radio emission flux from the “quiet” Sun, $F$ - the radio emission flux from the solar source). It turned out that the interrelationships of the active regions AR 9610, AR 9608, AR 9606 were the most interesting. It was registered 4 synchronous brightenings of solar sources AR 9610, AR 9608 at the moment of the observations: 8:38 UT, 9:02 UT, 9:50 UT, 10:30 UT. We recorded synchronous brightenings of solar sources at 1.92 cm, 2.24 cm, 2.74 cm, and 3.21 cm radio waves: at $\lambda=2.24 cm$ – $\Delta(F)=(0.24 \div 0.88)$ s.f.u. and at $\lambda=3.21$ cm – $\Delta(F)=(0.21 \div 0.94)$ s.f.u. The detailed halo solar source is the magnetosphere, which was identified with all extensive AR 9608 region excepting the primary the most strong solar source of the active region radio emission. The angular size of halo is closed to the angular size of AR 9608 ($7.7 \arcmin$). The comparison of the brightening onset of the AR 9610, AR 9608 interacting active regions in the time interval (9:26 - 9:58 UT) and the discovered forestalling of the halo flux quick intensification at $\lambda=2.24$ cm and $\lambda=3.21$ cm pointed to the active process start in the AR 9608 solar source at $\lambda=3.21$ cm. As it was shown, the dynamics of the time intensity variation of solar sources at $\lambda=3.21$ cm, $\lambda$=2.74 cm is more complicated. It is demonstrated by against of the synchronous of the moments of the AR 9610 relative flux maxima with the $\lambda$ increase (Figure 1b).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We report on detection of coronal streamer trace on the night sky over the horizon.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A major goal in solar physics has during the last five decades been to find how energy flux generated in the solar convection zone is transported and dissipated in the outer solar layers. Progress in this field has been slow and painstaking. However, advances in computer hardware and numerical methods, vastly increased observational capababilities and growing physical insight seem finally to be leading towards understanding. Here we present exploratory numerical MHD models that span the entire solar atmosphere from the upper convection zone to the lower corona. These models include non-grey, non-lte radiative transport in the photosphere and chromosphere, optically thin radiative losses as well as magnetic field-aligned heat conduction in the transition region and corona.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html