So at last we come to the end of our meeting! I have the honor of being the last speaker at Symposium 240, and apparently the last speaker of the GA itself! I will keep my comments very brief, so that you all may experience a few more minutes of sightseeing or perhaps another fine Czech beer before beginning your travels home.

A massive black hole at the center of a dense stellar system, such as a globular cluster or a galactic nucleus, is subject to a random walk due gravitational encounters with nearby stars. It behaves as a Brownian particle, since it is much more massive than the surrounding stars and moves much more slowly than they do. If the distribution function for the stellar velocities is Maxwellian, there is a exact equipartition of kinetic energy between the black hole and the stars in the stationary state. However, if the distribution function deviates from a Maxwellian form, the strict equipartition cannot be achieved.

The deviation from equipartition is quantified in this work by applying the Tsallis q-distribution for the stellar velocities in a q-isothermal stellar system and in a generalized King model.

Submillimetre (submm) astronomy is the prime technique to unveil the birth and early evolution of a broad range of astrophysical objects. It is a relatively new branch of observational astrophysics which focuses on studies of the cold Universe, i.e., objects radiating a significant – if not dominant – fraction of their energy at wavelengths ranging from ∼ 100 μm to ∼ 1 mm. Submm continuum observations are particularly powerful to measure the luminosities, temperatures and masses of cold dust emitting objects. Examples of such objects include star-forming clouds in our Galaxy, prestellar cores and deeply embedded protostars, protoplanetary disks around young stars, as well as nearby starburst galaxies and dust-enshrouded high-redshift galaxies in the early Universe.

We have developed a neural network based technique for identifying quasars from the photometric database of the Sloan Digital Sky Survey (SDSS). We have queried the SDSS data release 5 (DR5) to produce a dataset of spectroscopically identified samples of unresolved objects consisting of quasars and stars which forms the training set.

Processing long-baseline interferometry data presents a unique set of complications: How does one derive relative astrometry from interferometric data? How can 1-D interferometric results be used to solve a 2-D orbit? How can baseline-only solutions be combined with historical data and how should interferometric data be published so that they can be combined with archived data? What new techniques for interferometers are coming on line? This paper contains a brief review of interferometric data analysis in the context of binary star astrometry.

We have conducted deep near-infrared surveys of the Sh-2 255, W3 Main and NGC 7538 massive star forming regions using simultaneous observations of the JHKs-band with the near-infrared camera SIRIUS on the UH 88-inch telescope and with SUBARU. The near-infrared surveys cover a total area of ~ 72 arcmin2 of three regions with 10-σ limiting magnitudes of ~ 19.5, 18.4 and 17.3 in J, H and Ks-band, respectively. Based on the color-color and color-magnitude diagrams and their clustering properties, the candidate young stellar objects are identified and their luminosity functions are constructed in Sh-2 255, W3 Main and NGC 7538 star forming regions. A large number of previously unreported red sources (H-K > 2) have also been detected around these regions. We argue that these red stars are most probably pre-main-sequence stars with intrinsic color excesses. The detected young stellar objects show a clear clustering pattern in each region: the Class I-like sources are mostly clustered in molecular cloud region, while the Class II-like sources are in or around more evolved optical HII regions. We find that the slopes of the Ks-band luminosity functions of Sh-2 255, W3 Main and NGC 7538 are lower than the typical values reported for the young embedded clusters, and their stellar populations are primarily composed of low mass pre-main-sequence stars. From the slopes of the Ks-band luminosity functions, we infer that Sh-2 255, W3 Main and NGC 7538 star forming regions are rather young (age ≤ 1 Myr).

Photometric redshifts technique and red sequence technique are used in order to analyze the clustering of galaxies in the environments of 4 radio galaxies with redshifts z>0.6.

We obtained steady solutions of optically thin two-temperature magnetized accretion disks around a black hole. We included relativistic bremsstrahlung cooling, synchrotron cooling and inverse Compton effects and assumed that the disk is threaded by toroidal magnetic field. We found that a magnetic pressure dominated new branch, which we call a ‘low-β branch’, appears in the thermal equilibrium curves. The luminosity of the optically thin, magnetically supported disk can exceed 10% of the Eddington luminosity (0.1 LEdd).

S284 is a diffuse HII region located in the anti-centre of the galactic disk (l=212, b=−1.3), at a distance of 5.5 kpc and it is relatively isolated. S284 harbours a cluster of stars in its centre known as Dolidze 25 (also known as C 0642+0.03). A spectroscopic study of the cluster sources (Lennon et al. 1990, A&A, 240, 349) revealed: a) the spectral types of these central sources and b) the low metallicity of the cluster (a factor six lower than the solar metallicity). The age of the cluster (6 Myr) has been determined through isochrone fitting of precision photometry (Turbide & Moffat, 1993, AJ, 105, 1831).

We have conducted Spitzer-IRAC observations of 0.9x1.2 degrees around S284 in the four IRAC bands (3.6, 4.5, 5.8 and 8.0 μm). These data provide us with an unprecedented perspective of the dust component toward S284. We also present complementary observations with the WFC-INT (Roque de los Muchachos) in the Hα filter. The inspection of the images reveals the existence of: i) Rings of dust that constraint the ionised gas, ii) Elephant trunks stretching toward the centre of the main HII region, namely the cluster Dolidze 25 and iii) various spatial scales (4 main shells and 22 knots).

We have calculated the dynamical age of the central HII region (S284) in a very simple pressure-driven scenario, using the strong-shock approximation. The resultant age of the main shell is 8 Myr, in good agreement with the estimated age of the central cluster (Dolidze 25). The presence of another two smaller ionised bubbles (with diameters of 3′ and 5′, respectively) located at the rim of this HII region suggests a later generation of high-mass star-forming regions. The color-color diagram of the IRAC photometry betrays the existence of several Class I objects, most of which are located at the rim of the most prominent shell.

Multi-wavelength photometry has been gathered to construct the Spectral Energy Distribution of the 22 blobs detected toward S284. The SEDs reveal luminosities corresponding to low- and intermediate-mass stars.

We conclude that the remarkable symmetry of the main HII bubble, the spectra of masses harboured by the different blobs around it, and most importantly, the uniform presence of elephant trunks that stretch toward the centre can be best explained by the growth of dynamical instabilities in a collected layer (Garcia-Segura & Franco, 1996, ApJ, 469, 171). In the context of this hypothesis, the low metallicity of the environment would significantly determine the length and stability over time of the elephant trunks.

Observations in the Chandra Deep Field South (CDFS) have provided us with a useful set of data in the optical (COMBO-17), near-infrared (GOODS JHK), and mid-infrared (GOODS IRAC bands 1,2) wavelength regimes to test and improve a new spectral galaxy template library, designed to operate in the rest-frame wavelength range between 0.1 and 5 microns. In this range the stellar continuum and emission lines from HII regions dominate the Spectral Energy Distribution (SED) of galaxies. The new library is based on a self-consistent two-burst model, that has been developed in order to reproduce the star formation histories of different types of galaxies more accurately than single-burst histories and thus provides a better match to real galaxy spectra, as well as more reliable mass-to-light ratios. The spectral library is built by using a population synthesis code (PEGASE) assuming a Kroupa (2003) initial mass function. An old burst of exponentially decaying star formation with an initial metallicity of 0.1 solar is followed by a very recent (60 Myr old) second burst in order to reproduce the spectra of actively star forming blue galaxies. In addition, the templates include dust extinction of various strengths. For the multi-color classification the spectral library is red-shifted between z + 0 and z + 2.5 and converted into the 21 colors which have been observed by COMBO-17 plus its near- and mid-infrared extensions provided by the public GOODS data.

Until a few years ago, the common paradigm for the formation of Globular Clusters (GCs) was that they constitute a ‘simple stellar population’ in which all the stars were formed from a chemically homogeneous cluster medium within a relatively short interval of time, at the beginning of the galactic life. In recent years, the spectroscopic information on the low luminosity (turnoff) cluster stars have extended to the unevolved stars the recognition that chemical anomalies are a common feature of GCs and not an exception. This has provoked a revolution in the simple view of GC formation, and requires an adequate dynamical modelling including gas dynamics. It is by now well accepted that at least two different stellar components are common in most GCs. These are almost unequivocally identified with (i) a first stellar generation, which gave origin to stars of all masses; and (ii)) a second generation, born from the ejecta of the most massive asymptotic giant branch stars of the first generation, in the first 100–200 Myr from the first burst of star formation. A ‘third’ population is present only in some GCs, and is more difficult to be understood. It is characterized by stars having a huge helium content (Y ≃ 0.4, if stellar modelling is reasonable) and extreme chemical anomalies in the proton capture elements (Na, O, Al). The status of understanding of the GC properties, based on our most recent models of stellar evolution, is discussed.

We present the optical/NIR spectrum of the afterglow of GRB 050904 obtained with the Faint Object Camera And Spectrograph on the Subaru 8.2m telescope taken 3.4 days after the burst. It is, as of June 2006, the only GRB with a known redshift larger than 6. The spectrum shows a clear continuum at the long wavelength end of the spectrum with a sharp cutoff at around 900nm due to Lyα absorption at a redshift of 6.3 with a damping wing. Little flux is present in the waveband shortward of the Lyα break. A system of absorption lines of heavy elements at redshift z = 6.295±0.002 were also detected, yielding a precise measurement of the largest known redshift of a GRB. Analysis of the silicon and sulphur absorption lines suggests a dense environment around the GRB with the metallicity larger than 0.1 solar, providing unique information on the galaxy and star forming region at z>6. This observation has shown that GRB is a powerful probe of the early universe.

The method of spectra disentangling has been applied in many studies on different stellar systems up to the distance of Andromeda Galaxy. In some of these applications the underlying assumptions are not precisely satisfied. This is why new generalizations of the method are needed. Ways to overcome these problems are discussed here.

The evolutionary phases in going from a Type Ia supernova explosion to a 1000-yr-old remnant are reviewed. The explosion sets up the density and composition structure of the ejecta and can have radiative effects on the surroundings. The early shock interactions may be observable at radio and X-ray wavelengths if the circumstellar density is sufficiently high. The later interaction with the interstellar medium is affected by the collisionless shock physics and hydrodynamic instabilities.

We discuss problems of the reference radio source selection.

The role of primordial CH molecules in the first structures formation epoch is considered. We discuss the plausibility of observing protostructures in the Dark Age epoch of the Universe by studying the rotational structure of the CH molecule. It is stressed that considerable abundances of this molecule could be formed for different Inhomogeneous BBN models, which could lead to observable spectral-spatial fluctuations in the CMBR spectrum. The calculation is carried out for the Lambda-CDM cosmology and for typical first structures physical conditions. The chemical evolution of the structures is followed numerically, and the optical depth for the most important ground rotational transitions of the CH molecule are proposed. It is shown that under reasonable conditions the primordial CH molecule can be observed with mm-telescopes under construction.

Binaries are critical tools that drive stellar systems; which play a major role in galactic dynamics. Internal evolution of globular clusters, e.g., due to evolution of binaries, can be modulated by external effects, like tidal shocks (e.g., Chernoff & Weinberg 1990). There are well-established relations between dynamical properties of globular clusters and their galactrocentric distance, R(g). A characteristic one is: D(1/2) ≈ [R(g)]1/2, where D(1/2) is the diameter containing half the mass / luminosity in projection (van den Bergh et al. 1991). This relation could be a result of tidal evaporation of clusters and feedback of forming protoclusters (Surdin, 1995). A similar limitation of globular cluster distributions is obtained in the half-mass density kinetic temperature plot and used in many cluster formation scenarios (Muray & Lin 1992). This relationship should have an explanation on the basis of dynamic evolution of the cluster population.

The V and R light curves for 30 RR Lyrae stars in M15 were used to calculate their physical parameters. The Blazhko effect, previously reported in V12, was not detected. The determined values of the iron content and distance of the cluster are: [Fe/H] = −1.98 ± 0.24 and d = 8.67 ± 0.41 kpc, respectively. The mean values of the physical parameters determined for the RR Lyrae stars place the cluster precisely into the sequences Oosterhoff type – metallicity and metallicity – effective temperature, valid for globular clusters.

We present a study of the properties of circumstellar dust in symbiotic Miras during sufficiently long time intervals of minimal obscuration. The published JHKL magnitudes of o Ceti, RX Pup, KM Vel, V366 Car, V835 Cen, RR Tel and R Aqr have been collected. In order to investigate their long-term variations, we removed the Mira pulsations to correct their light curves. Assuming spherical temperature distribution of the dust in the close neighbourhood of the Mira, the DUSTY code was used to solve the radiative transfer in order to determine the dust temperature and its properties in each particular case.

The preliminary results of this systematic study of dust envelopes in symbiotic stars with Miras as cool components provide information on nature of dust in these objects.

Results of the last observations of solar sporadic radio emission at the UTR-2 radio telescope (Kharkov, Ukraine) at the frequencies 10 - 30 MHz are presented. The use of new backend facilities, the DSP and 60-channel spectrometer, allows us to obtain data with time resolution up to 2 ms and frequency resolution of 12 kHz in the continuous frequency band 12 MHz. Usual Type III bursts, Type IIIb bursts, U- and J-bursts in the decameter range are discussed. Special attention is paid to detection and analysis of Type II bursts and their properties, newly discovered fine time structures of Type III bursts, Type III-like bursts, s-bursts, new observational features of drift pair bursts, and ‘absorption’ bursts.