Forty five limb CMEs related with eruptive prominences and/or near-to-limb post-eruptive arcades have been tested. It is shown that CMEs can be divided into two groups. The first group includes coronal mass ejections whose “2α” latitude angular sizes apparent in the plane of the sky remain unchanged within measurement accuracy of several degrees. The second one is formed by CMEs that expand “non-radially”, namely, their angular sizes increase by the relative value (10-30)% up to the position of the ejection front RF = Rαm and run to the maximal value 2αm at this distance. It has been found that CMEs of the second type are, on the average, wider, faster and have an outer shell brighter and with higher plasma density for long distances. It is shown that on average Rαm increases as 2αm rises.

The heliospheric magnetic field and the solar wind are behaving differently in the current solar minimum, compared to the previous minimum. The radial component of the heliospheric magnetic field, and thus the average value of the component of the solar magnetic field that opens into the heliosphere, the so-called open magnetic flux of the Sun, is lower than it was in the previous solar minimum; in fact, lower than in any previous solar minimum for which there are good spacecraft observations. The mass flux, the ram pressure, and the coronal electron temperature as measured by solar wind charge states are also lower in the current minimum compared to the previous one. This situation provides an opportunity to test some of the concepts for the behavior of the heliospheric magnetic field and the solar wind that have been developed; to improve these theories, and to construct a theory for the solar wind that accounts for the observed behavior throughout the solar cycle, including the current unusual solar minimum.

Recent work on coronal polar plumes (Gabriel et al. 2003, 2005) has aimed at determining the outflow velocity in plume and interplume regions, using the Doppler dimming technique on oxygen VI observations by SUMER and UVCS on SOHO. By comparing observations of SOHO/EIT with plume modelling, we show that the major part of plumes is the result of chance alignments along the line-of-sight of small enhancements in intensity. This confirms the so-called curtain model. These plumes can be attributed to reconnection activity along the boundaries of supergranule cells. A second population of plumes has a lower abundance and arises from surface bright points having a particular magnetic configuration. New observations using the Hinode/EIS spectrometer are in progress, with the aim of providing further insight for this model.

The Sun is by far the largest reservoir of matter in the solar system and contains more than 99% of the mass of the solar system. Theories on the formation of the solar system maintain that the gravitational collapse is very efficient and that typically not more than one tenth from the solar nebula is lost during the formation process. Consequently, the Sun can be considered as a representative sample of interstellar matter taken from a well mixed reservoir 4.6 Gy ago, at about 8 kpc from the galactic center. At the same time, the Sun is also a faithful witness of the composition of matter at the beginning of the evolution of the solar system and the formation of planets, asteroids, and comets. Knowledge on the solar composition and a fair account of the related uncertainties is relevant for many fields in astrophysics, planetary sciences, cosmo- and geochemistry. Apart from the basic interest in the chemical evolution of the galaxy and the solar system, compositional studies have also led to many applications in space research, i.e., it has helped to distinguish between different components of diffuse heliospheric matter. The elemental, isotopic, and charge state composition of heliospheric particles (solar wind, interstellar neutrals, pickup ions) has been used for a multitude of applications, such as tracing the source material, constraining parameters for models of the acceleration processes, and of the transport through the interplanetary medium. It is important to realize, that the two mainstream applications, as outlined above – geochemistry and cosmochemistry on one side, and tracing of heliospheric processes on the other side – are not independent of each other. Understanding the physical processes, e.g., of the fractionation of the solar wind, is crucial for the interpretation of compositional data; on the other hand, reliable information on the source composition is the basis for putting constraints on models of the solar wind fractionation.

We have found a similar tendency of the spatial dynamics at 34 GHz for all major temporal sub-peaks of the burst with the re-distribution of the brightness from the footpoints (on the rising phase of each peak) to the upper part of the loop (on the decay phase). Observed dynamics is interpreted by the re-distribution of accelerated electrons number density with their relative enhancement in the loop top. Results of diagnostics show that the ratio of non-thermal electron number density in the loop top and in the footpoint changes 7 times from the peak to decay phase. Model simulations by solving the Fokker-Planck equation allowed to determine an injection type which is able to result in necessary dynamics of energetic electrons.

We consider some general aspects of twisted magnetic flux ropes (TFR), which are thought to play a fundamental role in the structure and dynamics of large scale eruptive events. We first discuss the possibility to show the presence of a TFR in a pre-eruptive configuration by using a model along with observational informations provided by a vector magnetograph. Then we present, in the framework of a generic model in which the coronal field is driven into an evolution by changes imposed at the photospheric level, several mechanisms which may lead to the formation and the disruption of a TFR, including the development of a MHD instability, and we discuss the issues of the energy and helicity contents of an erupting configuration. Finally we report some results of a recent and more ambitious approach to the physics of TFRs in which one tries to describe in a consistent way their rising through the convection zone, their emergence through the photosphere, and their subsequent evolution in the corona.

The supersonic solar wind is highly variable on all time scales near the Sun but fluctuations are moderated by self-interaction as this plasma moves outward. The solar wind runs into many obstacles on its way out. The neutrals from the interstellar medium slow it down. Magnetospheres and interplanetary coronal mass ejections (ICMEs) cause shocks to form so that the flow can divert around these obstacles. Finally the solar wind is stopped by the circum-heliospheric interstellar medium (CHISM); it slows at the termination shock and then turns down the heliotail. The shocks and sheaths formed by these interactions cover scales which vary by orders of magnitude; some aspects of these shocks and sheaths look very similar and some very different. We discuss solar wind evolution, interaction with the neutrals from the CHISM, foreshocks, shock structure, shock heating, asymmetries, and sheath variability in different sheath regions.

We report on the statistical relationships between solar flares and coronal mass ejections (CMEs) observed during 1996-2007 inclusively. We used soft X-ray flares observed by the Geostationary Operational Environmental Satellite (GOES) and CMEs observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission. Main results are (1) the CME association rate increases with flare's peak flux, fluence, and duration, (2) the difference between flare and CME onsets shows a Gaussian distribution with the standard deviation σ = 17 min (σ = 15 min) for the first (second) order extrapolated CME onset, (3) the most frequent flare site is under the center of the CME span, not near one leg (outer edge) of the CMEs, (4) a good correlation was found between the flare fluence versus the CME kinetic energy. Implications for flare-CME models are discussed.

The observations of 3 and 5 minute oscillations in sunspots present information on propagation of MHD waves in the magnetic tubes of sunspots. We present a comparison of wavelet spectra of radio flux oscillations at λ = 1.76 cm and oscillations of longitudinal component of the velocity at the chromosphere in sunspot umbra and penumbra in AR 10661 (2004, Aug 18). The radio maps of the Sun obtained with the Nobeyama Radioheliograph were used. The spatial resolution of the radio data was about 10-15 arcsec, and 10 sec cadence was used. On the radio maps sunspot-associated sources were identified and time profiles of their maximum brightness temperatures for each radio source were calculated. Radio data consists of information of oscillations of plasma parameters (in the regions with magnetic field B = 2000 G) at the level of the chromosphere-corona transition region. The optical observations were carried out at Sayan observatory. These data included information on longitude component of the magnetic field at the photosphere (line Fe I 6569 Å) and longitudinal component of the velocity at the chromosphere (line Hα was used). Comparing the wavelet diagrams covering the same periods of observations at radio and optics showed that some wave trains of time profiles are very similar in both kinds of observations (similar oscillation frequencies and their drifts, variations of amplitudes), however, some significant differences were also registered. The best similarity in optical and radio oscillations was found when the active region (AR) was near the center of the solar disk. The phase shifts between the two kinds of observations reflecting the propagation of MHD waves were also analyzed.

The differential rotation of the compact elements of the large-scale magnetic fields is studied using Solar Synoptic Charts (1966–1986). It is revealed that compact magnetic elements with the similar polarity of the polar magnetic field of the Sun have a larger rotation rate than the elements with the opposite polarity at all stages in the cycle.

From the comparison of the experimental measuring data of the solar magnetic elements there are received the results: a) The differential rotations of the compact magnetic elements with negative and positive polarities have the similar behavior for the solar 20 and 21 cycles; b) It is established that in the rotation rate of compact magnetic elements there are present some variations at the time of polarity reversal of the Sun.

There is assumed that the physical understanding of the connections of differential rotation of compact magnetic elements and polarity reversal of the Sun depends upon establishing a connection between the temporal variability of spatially resolved solar magnetic elements and polar reversals.

The Magellanic Clouds are often characterized as “irregular” galaxies, a term that implies an overall lack of organized structure. While this may be a fitting description of the Small Cloud, the Large Magellanic Cloud, contrary to popular opinion, should not be considered an irregular galaxy. It is characterized by a distinctive morphology of having an offset stellar bar and single spiral arm. Such morphology is relatively common in galaxies of similar mass throughout the local Universe, although explaining the origin of these features has proven challenging. Through a number of recent studies we are beginning to get a better grasp on what it means to be a Magellanic spiral. One key result of these works is that we now recognize that the most unique aspect of the Magellanic Clouds is not their structure, but, rather, their proximity to a larger spiral such as the Milky Way.

At low metallicity, B-type stars show lower loss of mass and, therefore, angular momentum so that it is expected that there are more Be stars in the Magellanic Clouds than in the Milky Way. However, till now, searches for Be stars were only performed in a very small number of open clusters in the Magellanic Clouds. Using the ESO/WFI in its slitless spectroscopic mode, we performed a Hα survey of the Large and Small Magellanic Cloud. Eight million low-resolution spectra centered on Hα were obtained. For their automatic analysis, we developed the ALBUM code. Here, we present the observations, the method to exploit the data and first results for 84 open clusters in the SMC. In particular, cross-correlating our catalogs with OGLE positional and photometric data, we classified more than 4000 stars and were able to find the B and Be stars in them. We show the evolution of the rates of Be stars as functions of area density, metallicity, spectral type, and age.

At the 1998 IAU Symposium on the Magellanic Clouds, Dr. Robert Petre observed that we were reaching a time where it was possible “to study the MC SNRs at a level of detail comparable with many Galactic remnants”, while retaining the benefits of a global view in the MCs. Over the past decade, many researchers have taken advantage of these newly accessible populations. New MC-wide surveys at various wavelengths have enabled broader searches for SNR candidates, extending our census of MC SNRs to less prominent objects — older SNRs, SNRs in complex regions, et cetera. The use of light-echoes has provided a new avenue to probe young SNRs. Higher spatial and spectral resolutions in many wavelength regimes have enabled detailed studies of individual remnants, revealing progenitor types, pulsar-wind nebulae, expansion details, and environmental effects.

Perhaps the newest conceptual development is the increasing use of the MC SNRs to study physical problems of wider significance to many fields of astronomy. For example, researchers have examined the energy and hot gas inputs of MC SNRs to the ISM, including their collective effects within superbubbles, in order to evaluate their effects on stellar feedback cycles in a galaxy. Other scientists have investigated the fraction of SNR energies going to the acceleration of cosmic rays, which has significant implications for the role of SNRs in cosmic-ray production. Most recently, the onslaught of Spitzer data has led to new exploration of dust in MC SNRs, allowing us to probe dust creation, depletion, and destruction in the MC SNR populations. In summary, the study of SNRs in the MCs appears to have “come of age” over the past decade, becoming a mature field with rich potential for future scientific work.

Detailed 4.8 and 8.64 GHz radio images of the entire Large and Small Magellanic Clouds with half-power beamwidths of 35″ at 4.8 GHz and 22″ at 8.64 GHz have been obtained using the Australia Telescope Compact Array. Full polarimetric observations were made. Several thousand mosaic positions were used to cover an area of 6° on a side for the LMC and 4.5° for the SMC. These images have sufficient spatial resolution (~ 8 and 5 pc, respectively) and sensitivity (3σ of 1.5 mJy beam−1) to identify most of the individual supernova remnants and H ii regions and also, in combination with available data from the Parkes 64-m telescope, the structure of the smooth emission in these galaxies. We have recently revised the early data analysis (Dickel et al. 2005) by increasing the CLEAN cutoff limit to recover more intermediate-spacing data and thus present more accurate brightnesses for extended sources. In addition, limited data using the sixth antenna at 4.5 – 6 km baselines are available to distinguish bright point sources (< 3″ and 2″, respectively) and to help estimate sizes of individual sources smaller than the resolution of the full survey. The resulting database will be valuable for statistical studies and comparisons with X-ray, optical, and infrared surveys of the LMC with similar resolution.

The interstellar gas of the Magellanic System is subject to the harassment of tidal interactions on galaxy-wide scales and stellar energy feedback on sub-galactic scales. H i surveys of the Magellanic System have produced spectacular images of the tidally displaced interstellar gas in the Magellanic Bridge and Streams. Multi-wavelength observations of the interstellar gas in the Magellanic Clouds have revealed gas components in physical conditions ranging from cold molecular cloud to hot ionized coronal gas. While stellar energy feedback is responsible for heating and dispersing interstellar gas, it can also compress ambient cloud to form stars. I will use Chandra, XMM-Newton, FUSE, HST, Spitzer, ATCA, and other ground-based observations to illustrate the interplay among massive stars, interstellar medium, and star formation.

We used the red clump stars from the Optical Gravitational Lensing Experiment (OGLE II) survey and the Magellanic Cloud Photometric Survey (MCPS), to estimate the line-of-sight depth. The observed dispersion in the magnitude and colour distribution of red clump stars is used to estimate the line-of-sight depth, after correcting for the contribution due to other effects. This dispersion due to depth, has a range from minimum dispersion that can be estimated, to 0.46 mag (a depth of 500 pc to 10.44 kpc), in the LMC. In the case of the SMC, the dispersion ranges from minimum dispersion to 0.35 magnitude (a depth of 665 pc to 9.53 kpc). The thickness profile of the LMC bar indicates that it is flared. The average depth in the bar region is 4.0 ± 1.4 kpc. The halo of the LMC (using RR Lyrae stars) is found to have larger depth compared to the disk/bar, which supports the presence of an inner halo for the LMC. The large depth estimated for the LMC bar and the disk suggests that the LMC might have had minor mergers. In the case of the SMC, the bar depth (4.90 ± 1.23 kpc) and the disk depth (4.23 ± 1.48 kpc) are found to be within the standard deviations. We find evidence for an increase in depth near the optical center (up to 9 kpc). On the other hand, the estimated depth for the halo (RR Lyrae stars) and disk (RC stars) for the bar region of the SMC is found to be similar. Thus, increased depth and enhanced stellar as well as H i density near the optical center suggests that the SMC may have a bulge.

Because of its proximity, the Small Magellanic Cloud provides a unique opportunity to map the polycyclic aromatic hydrocarbon (PAH) emission from photo-dissociation regions (PDRs) in a low-metallicity (12 + log(O/H) ~ 8) galaxy at high spatial resolution in order to learn about their abundance and physical state. We present mid-IR spectral mapping observations of star-forming regions in the Small Magellanic Cloud obtained as part of the Spitzer Spectroscopic Survey of the SMC (S4MC) project. These observations allow us to map the distribution of PAH emission in these regions and the measure the variation of PAH band strengths with local physical conditions. In these proceedings we discuss preliminary results on the physical state of the PAHs, in particular their ionization fraction.

We report the results of our project devoted to study the chemical enrichment history of the field population in the Magellanic Clouds using Ca ii triplet spectroscopy.

The Magellanic Clouds offer unique opportunities to study star formation both on the global scales of an interacting system of gas-rich galaxies, as well as on the scales of individual star-forming clouds. The interstellar media of the Small and Large Magellanic Clouds and their connecting bridge, span a range in (low) metallicities and gas density. This allows us to study star formation near the critical density and gain an understanding of how tidal dwarfs might form; the low metallicity of the SMC in particular is typical of galaxies during the early phases of their assembly, and studies of star formation in the SMC provide a stepping stone to understand star formation at high redshift where these processes can not be directly observed. In this review, I introduce the different environments encountered in the Magellanic System and compare these with the Schmidt-Kennicutt law and the predicted efficiencies of various chemo-physical processes. I then concentrate on three aspects that are of particular importance: the chemistry of the embedded stages of star formation, the Initial Mass Function, and feedback effects from massive stars and its ability to trigger further star formation.

I use high resolution N-body/SPH simulations to model the new proper motion of the Large Magellanic Cloud (LMC) within the Milky Way (MW) halo and investigate the effects of gravitational and hydrodynamical forces on the formation of the Magellanic Stream (MS). Both the LMC and the MW are fully self consistent galaxy models embedded in extended cuspy ΛCDM dark matter halos. I find that ram-pressure from a low density ionized halo is sufficient to remove a large amount of gas from the LMC's disk forming a trailing Stream that extends more than 120 degrees from the Cloud. Tidal forces elongate the satellite's disk but do not affect its vertical structure. No stars become unbound showing that tidal stripping is almost effectless.