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.

We recently launched a comprehensive ground based (ESO/VLT/NTT) and space (HST & SST) study of the present and past star formation in the Small Magellanic Cloud (SMC), in clusters and in the field, with the goal of understanding how star and cluster formation occur and propagate in an environment of low metallicity, with a gas and dust content that is significantly lower than in the Milky Way. In this paper, we present some preliminary results of the “young cluster” program, where we acquired deep F555W (~V), and F814W (~I) HST/ACS images of the four young and massive SMC star clusters: NGC 346, NGC 602, NGC 299, and NGC 376.

A survey for NEO aiming at 90% completeness for a given size range cannot ignore that a significant fraction of the population is observable essentially only at low solar elongation, in the so called “sweet spots” There are several penalties for such low elongation: poorer observing conditions imply a lower limiting magnitude, shorter available time in each night and a more difficult orbit determination. Our aim is to show that these difficulties can be overcome. We have tested the observation procedures and the mathematical methods of orbit determination on two sweet spot test runs. One was performed at ESO La Silla in Jan–Feb 2005, the other at Mauna Kea in Sept–Dec 2005. The results of the tests are presented in this paper; the observed area was not large enough (especially at Mauna Kea) to discover a significant number of new NEO, the purpose was rather to identify the problems. These tests have allowed us to identify all the key elements to be accounted for in the strategy for a successful sweet spot NEO survey. When very short arc observations from different nights have to be identified, a specific difficulty occurs at the sweet spots: the same set of observations from three nights can be fitted to two incompatible orbits, in most cases including one NEO and one MBA. This can lead to two different failures (false positive, false negative) in deciding whether a NEO has been discovered. The classical theory of preliminary orbits shows that three observations at an elongation less than 116.5° can be compatible with two different orbits. From this theory we have derived an algorithm to find the alternate solution, if it exists, when only one is available. In this way we have generated a set of examples of possible discoveries with two well determined but incompatible solutions. Most of the MBA-NEO alternatives have been solved by finding a known MBA which could be identified; in two cases the MBA solution has been confirmed by a later observation.

Near infrared dust extinction mapping is opening a new window on molecular cloud research. Applying a straightforward technique to near infrared large scale data of nearby molecular complexes one can easily construct density maps with dynamic ranges in column density covering, 3σ~ 0.5 < AV< 50 mag or 1021<N<1023 cm−2. These maps are unique in capturing the low column density distribution of gas in molecular cloud complexes, where most of the mass resides, and at the same time allow the identification of dense cores (n~104cm−3) which are the precursors of stars. For example, the application of this technique to the nearby Pipe Nebula complex revealed the presence of 159 dense cores (the largest sample of such object in one single complex) whose mass spectrum presents the first robust evidence for a departure from a single power-law. The form of this mass function is surprisingly similar in shape to the stellar IMF but scaled to a higher mass by a factor of about 3. This suggests that the distribution of stellar birth masses (IMF) is the direct product of the dense core mass function and a uniform star formation efficiency of 30%±10%, and that the stellar IMF may already be fixed during or before the earliest stages of core evolution. We are now extending this technique to extra-galactic mapping of Giant molecular Clouds (GMCs), and although a much less straightforward task, preliminary results indicate that the GMC mass spectrum in M83 and Centaurus A is a power-law characterized by α~−2 unlike CO results which suggest α~−1.

Since the last IAU symposium on planetary nebulae (PNe), several deep spectroscopic surveys of the relatively faint optical recombination lines (ORLs) emitted by heavy element ions in PNe and H II regions have been completed. New diagnostic tools have been developed thanks to progress in the calculations of basic atomic data. Together, they have led to a better understanding of the physical conditions under which the various types of emission lines arise. The studies have strengthened the previous conjecture that nebulae contain another component of cold, high metallicity gas, which is too cool to excite any significant optical or UV CELs and is thus invisible via such lines. The existence of such a plasma component in PNe and possibly also in H II regions provides a natural solution to the long-standing problem in nebular astrophysics, i.e. the dichotomy of nebular plasma diagnostics and abundance determinations using ORLs and continua on the one hand and collisionally excited lines (CELs) on the other.

During its definition phase, ESA's Cornerstone mission Gaia was designed to perform extremely accurate photometry in 10 medium plus 5 broad bands and to collect about 90 epoch spectra with a resolving power of 11500 and a wavelength range 8480–8740Å (centered on the CaII triplet in the far red). Combining epoch photometry from the ground and the Hipparcos mission with ground-based spectra strictly simulating Gaia ones, we have investigated in a series of papers the performance expected from Gaia on SB2 EBs. We review here the results we obtained. The Gaia design is now under major revision, and its impact on EBs will be briefly addressed.

The problem of initial linking of asteroids is of increasing interest for the next generation surveys. During the first week after discovery elliptical elements are very uncertain and other methods are used. A summary is given of 7 initial linking methods. There are two different types: In one, a search area is computed on a second night from the known and undoubtedly linked positions, typically on the first night. The other type assumes candidates which are then checked by the computation of O – C residuals of an orbit. Computations may be classified as belonging to the 3-dimensional space or the 2-dimensional sky-plane. A new basis, with a simpler computational algorithm, is given for the widely used Väisälä method. For a new N-Observation Orbit method a simple, efficient PC-programme is given.

SS 433 is the only known persistent supercritical accretor, it may be very important for understanding ultraluminous X-ray sources (ULXs) located in external galaxies. We describe main properties of the SS 433 supercritical accretion disk and jets. Basing on observational data of SS 433 and published 2D simulations of supercritical accretion disks we estimate parameters of the funnel in the disk/wind of SS 433. We argue that the UV radiation of the SS 433 disk (∼ 50000 K, ∼ 1040 erg/s) is roughly isotropic, but X-ray radiation (∼ 107 K, ∼ 1040 erg/s) of the funnel is mildly anisotropic. A face-on SS 433 object has to be ultraluminous in X-rays (1040–41 erg/s). Typical time-scales of the funnel flux variability are estimated. Shallow and very broad (0.1-0.3c) and blue-shifted absorption lines are expected in the funnel X-ray spectrum.

The site testing program for the Thirty-Meter-Telescope (TMT) is monitoring the seeing conditions above several mountains. Observations are presented which show that the ground layer seeing (0 m–500 m above the ground) is influenced by the onset of free convection. It is shown that under radiation dominated conditions, indicating free convection of the atmosphere above the site, the occurence of the very best seeing conditions is supressed. A quantitative threshold for these conditions is given, allowing to estimate the shortterm future stability of the ground layer seeing.

The problem of light pollution became important mainly since 1960, by growth of urban development and using more artificial lights and lamps at the nighttimes. Optical telescopes share the same range of wavelengths as are used to provide illumination of roadways, buildings and automobiles. The light glow that emanates from man made pollution will scatter off the atmosphere and affects the images taken by the observatory instruments. A method of estimating the night sky brightness produced by a city of known population and distance is useful in site testing of the new observatories, as well as in studying the likely future deterioration of existing sites. Now with planning the Iranian National Observatory that will house a 2-metre telescope and on the way of the site selection project, studying the light pollution is propounded in Iran. Thus, we need a site with the least light pollution, beside other parameters, i.e. seeing, meteorological, geophysical and local parameters. The seeing parameter is being measured in our four preliminary selected sites at Qom, Kashan, Kerman and Birjand since two years ago using an out of focus Differential Image Motion Monitor. These sites are selected among 33 candidate sites by studying the meteorological data obtained from the local synoptic stations and the Meteosat. We measured and used the Walker's law to estimate the Sky brightness for three of these sites

The data obtained using an 8-inch Meade telescope with a ST7 CCD camera for above sites are consistent with the estimated values of the light pollution mentioned above.

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.

We describe a made-to-measure algorithm (χ2M2M) for constructing N-particle models of stellar systems from observational data (De Lorenzi Debattista, Gerhard, et al. (2007)), extending earlier ideas by Syer & Tremaine (1996). The algorithm properly accounts for observational errors. We implemented this algorithm in a parallel code NMAGIC and carried out a sequence of tests to illustrate its power and performance: (i) We reconstructed an isotropic Hernquist (1990) model from density moments and projected kinematics including higher-order Gauss-Hermite moments (Gerhard (1993), van der Marel & Franx (1993)). We gave NMAGIC two initial models, made from distribution function (Debattista & Sellwood (2000)), with different density distributions to start with. While both recovered the correct differential energy distribution and intrinsic kinematics, that with density closer to the density of the final model had smaller final deviations from the target observables, and a narrower distribution of weights. (ii) We built a self-consistent oblate three-integral maximum rotator model and compared how the distribution function is recovered from integral field and slit kinematic data. In these experiments we gave the algorithm a difficult problem to solve. Since the target system was maximally rotating, the weights of all counter-rotating particles were zero. Using density observables and either slit or integral field kinematics, NMAGIC was asked to recover this maximally rotating model starting from an isotropic spherical system. A good fit to the kinematic constraint data was achieved. These experiments also showed the advantage of integral field data over slit data for constraining the model. The different applications show that the χ2M2M algorithm is practical, reliable and can be applied to various systems. High quality dynamical models of galaxies can be achieved which match targets to ~1σ for plausible uncertainties in the observables, and without symmetry restrictions. We conclude that χ2M2M holds great promise for unraveling the nature of galaxies.

Simulations of the chemical enrichment histories of ten Local Group (LG) dwarf galaxies are presented, employing empirically-derived star formation histories (SFHs), a rich network of isotopic and elemental nucleosynthetic yields, and a range of prescriptions for supernova (SN)-driven outflows. Our main conclusions are that (i) neutron-capture element patterns (particularly that of Ba/Y) suggest a strong contribution from low- and intermediate-mass stars (LIMS), (ii) neutron star mergers may play a relatively larger role in the nucleosynthesis of dwarfs, (iii) SN feedback alone can explain the observed gas fraction in dwarf irregulars (dIrrs), but dwarf spheroidals (dSphs) require almost all their gas to be removed via ram pressure and/or tidal stripping, (iv) the predicted heavy Mg isotope enhancements in the interstellar medium (ISM) of dwarfs may provide an alternate solution to claims of a varying fine structure (v) the gas lost from dwarfs have O,Si/C abundances in broad agreement with intergalactic medium abundances at redshifts 2<z<4, and (vi) the chemical properties of dSphs are well-matched by preventing galactic winds from re-accreting, whilst those of dIrrs are better-matched by incorporating metallicity-dependent cooling and re-accretion of hot winds. Finally, doubts are cast upon a claimed association between LG dSph UMaII and HVC Complex A.

We describe the present status of the mass discrepancy in the Upper HR Diagram.

We present results from a project aimed at better understanding the kinematics and metallicities of populous clusters in the LMC. In an effort to update previous [Fe/H] determinations, we have utilized FORS2 on the VLT to obtain infrared spectra for more than 200 stars in 28 LMC clusters. The absorption lines of the calcium II triplet were then used to calculate radial velocities and [Fe/H] for a sample of clusters spanning a large range of ages (~ 1-13 Gyr) and metallicities (−0.3 >[Fe/H]> − 2.0). We determine mean cluster velocities to typically 1.6 km s−1 and mean metallicities to 0.04 dex (random error). For eight of these clusters, we report the first spectroscopically determined metallicities based on individual cluster stars, and six of these eight have no published radial velocity measurements. Combining our data with archival HST/WFPC2 photometry, we find the newly measured cluster, NGC 1718, is one of the most metal-poor ([Fe/H] ~ −0.80), intermediate age (~ 2 Gyr) inner disk clusters in the LMC. Similar to what was found by previous authors, this cluster sample has motions consistent with that of a single rotating disk system, with no indication that the newly reported clusters exhibit halo kinematics. Additionally, our findings confirm previous results which show that the LMC lacks the metallicity gradient typically seen in non-barred spiral galaxies, suggesting that the bar is driving the mixing of stellar populations in the LMC. However, in contrast to previous work, we find that the higher metallicity clusters (≥−1.0 dex) in our sample show a very tight distribution (mean [Fe/H] = −0.48, σ = 0.09), with no tail toward solar metallicities. The cluster distribution is similar to what has been found for red giant stars in the bar, which indicates that the bar and the intermediate age clusters have similar star formation histories. This is in good agreement with recent theoretical models that suggest the bar and intermediate age clusters formed as a result of a close encounter with the SMC ~ 4 Gyr ago.

We present a study of a peculiar nebula MF16 associated with an Ultraluminous X-ray Source NGC6946 ULX-1. We use integral-field and long-slit spectral data obtained with the 6-m telescope (Russia). The nebula was for a long time considered powered by strong shocks enhancing both high-excitation and low-excitation lines. However, kinematical properties point to rather moderate expansion rates (VS ∼ 100÷200 km s−1). The total power of the emission-line source exceeds by one or two orders of magnitude the power observed expansion rate can provide, that points towards the existence of an additional source of excitation and ionization. Using CLOUDY96.01 photoionization code we derive the properties of the photoionizing source. Its total UV/EUV luminosity must be about 1040 erg/s.

Basic stellar structure dictates that stars of ∼ 100 M⊙ or more will be close to the Eddington limit, with luminosities in excess of 106 L⊙, and radiation pressure contributing prominently to the support against gravity. Although it is formally possible to generate static structure models of even more massive stars, recent studies of dense clusters show there is a sharp cutoff at masses above ∼ 150 M⊙. This talk examines the role of extreme mass loss is limiting the masses of stars, emphasizing in particular that continuum driving, possibly associated with structural instabilities of radiation dominated envelope, can lead to much stronger mass loss than is possible by the usual line-scattering mechanism of steady stellar winds.

However, population studies of very young, dense stellar clusters now suggest quite strongly that there is a sharp cutoff at masses above ca. 150 M⊙ (see, e.g., the talk by Sally Oey, in this JD 05, p. 206). This is sometimes attributed to a mass limit on star formation by accretion processes, though there are competing formation scenarios by binary or cluster merging that would seem likely to lead to formation of even higher mass stars (see talks in JD14 and S237).

So given the above rough coincidence of the observational upper mass limit with the Eddington-limit domain of radiation-pressure dominance, it seems associated instabilities in stellar structure might actually be a more important factor in this upper mass limit, leading to extreme mass loss in LBV and/or giant eruption events, much as inferred from circumstellar nebulae observed around high mass stars like eta Carinae and the Pistol star.

Three basic modeling approaches have been used to numerically simulate fluid turbulence and the banded zonal winds in the interiors and atmospheres of giant planets: shallow-water models, deep-shell Boussinesq models and deep-shell anelastic models. We review these models and discuss the approximations and assumptions upon which they are based. All three can produce banded zonal wind patterns at the surface. However, shallow-water models produce a retrograde (i.e., westward) zonal jet in the equatorial region, whereas strong prograde (i.e., eastward) equatorial jets exist on Jupiter and Saturn. Deep-shell Boussinesq models maintain prograde equatorial jets by the classic method of vortex stretching of convective columnar flows; however, they neglect the effects of the large density stratification in these giant planets. Deep-shell anelastic models account for density stratification and maintain prograde equatorial jets by generating vorticity as rising fluid expands and sinking fluid contracts, without the constraint of long thin convective columns.

The purpose: to emphasize, that there are some specific features of the development of science in the New Independent States (NIS) of the Former Soviet Union. These features demand enhanced attention of the organizers of the IHY. It is necessary to create effective mechanisms for the stimulation of the connection to world science of the dormant part of fundamental scientific knowledge of these countries, which has been saved up for fifty of years. Probably, the IHY is the last opportunity of rescuing the dormant part of this knowledge from full oblivion.

The method adopted is to discuss and analyse the general tendencies in science in the NIS by reference to individual cases, in particular for meteor astronomy.

Results: The features and history of the development of meteor astronomy during the existence of the Soviet Union and the subsequent period give a key to understanding of the problem. Meteor astronomy can be assumed to be a young science. It is an example of a cross-disciplinary science. It is an example of a science having a sharp rise, due to the project of the IGY and to subsequent geophysical projects. Meteor astronomy is a science directly connected with the launching of the first space satellite of the Earth and the evaluation of problems of meteoroid danger to space missions.

Commission 22 (Division III) of the IAU coordinated the development of meteor astronomy during the IGY. The known Soviet researcher of meteors V. Fedynskiy headed this Commission during four years since 1958. In the USSR numerous meteor centres were created and activated. The general management was concentrated in Moscow. Despite the close interaction under global projects of the Soviet Union with other countries, there still existed a language barrier. The language barrier, together with other reasons, has led to the creation in the USSR of a powerful meteor science, but only in the Russian language.

After the disintegration of the Soviet Union, the meteor centres have remained, but without ordinary central management. The scientific results have remained but as an isolated, inaccessible science published in English.

Conclusion: Reunification of the scientific achievements of the last few years in the NIS with international science should become the task of the IHY. Revival of the activity of the some of the centres will be useful.

Latitudinal structure with four zones: two sub polar and two equatorial with 22-year period of polarity change is clearly demonstrated. The auto-correlation of the magnetic field has been calculated for all latitudes from 75 N to 75 S to study its temporal variability on a short and on a long term scale. The meridional drift of the magnetic field with 2–3 years periodicities has been clearly evidenced in the both hemispheres.