We review the problem of particle acceleration in relativistic shocks or shear flows. We propose a converter mechanism, which operates via continuous conversion of accelerated particles from charged into neutral state and back, and show that it is capable of producing the highest energy cosmic rays.

Both the X-shaped radio galaxies and double-double radio galaxies (DDRGs) are suggested in the literature to be due to the binary-accretion disk interaction or to the coalescence of SMBBHs. These models suggest some relationship between the two types of radio sources. In this paper, we collected data from literatures for two samples of X-shaped and double-double radio galaxies together with a control sample of FRII radio galaxies and statistically investigate their properties.

We find that the wings of X-shaped radio galaxies and the outer and inner lobes of DDRGs tend to be perpendicular to the major axis of the host galaxy (or dust structures), while the active lobes orient randomly. Both X-shaped and double-double radio galaxies are low luminous FRII or FRI/FRII transitional radio sources with the similar dimensionless accretion rate ṁ ∼ 0.01, which is about the transitional accretion rate given in the literature.

All the statistic results can be reconciled if there is an evolutionary relationship between X-shaped and double-double radio galaxies, in the sense that X-shaped radio galaxies may be due to the interaction of active SMBBHs and accretion disk and DDRGs due to the removal of inner disk region and the coalescence of SMBBHs.

We numerically model winds driven by super star clusters (SSC) using the hydrodynamic code ZEUS with the new radiative cooling procedure. The importance of cooling on the wind dynamics depends on the properties of the central cluster: the energy and mass deposition rates Lsc and Ṁsc, and the cluster radius Rsc. Low mass clusters behave adiabatically, and their winds are well described by the solution of Chevalier & Clegg (1985). However, for larger Lsc and Ṁsc and/or smaller Rsc, cooling becomes important, and the wind enters the radiative regime in which the wind temperature quickly drops to 104 K at a small distance away from the cluster (Silich et al., 2004). There is no stationary wind solution for very energetic and compact clusters. This is expressed by the line of the critical luminosity Lcrit shown by the left panel as a function of Rsc.

In the case of SSC above the threshold line, the stagnation point Rst appears inside the cluster. It splits the cluster volume into two parts: the outer one with r > Rst where the wind velocity is always positive, and the inner one r < Rst where it has a complicated time-dependent profile. The mass inserted into the outer region leaves the cluster in a form of quasi-stationary wind, while most of the mass from the inner region either accumulates there or passes the inner boundary and eventually feeds further star formation. The middle figure shows that the stagnation point Rst asymptotically approaches the cluster radius Rsc with the increasing Lsc.

The right figure summarises several of our calculations for a cluster with an Rsc = 10 pc. It shows the amount of the mass Ṁout outflowing from the cluster depending on Lsc. It can be seen that Ṁout grows with Lsc following the power-law fit of the simulations Ṁout ≈ Lsc0.54. However, the fraction of the outflowing mass to the total mass deposited by the cluster Ṁsc decreases with Lsc from 100% for Lsc = Lcrit to several percent for Lsc = 5 × 1044 erg s−1.

The spatial power spectrum of the HI 21 cm intensity in the Small Magellanic Cloud (Stanimirovic et al. 1999) is a power law over scales as large as those of the SMC itself. It was interpreted as due to turbulence by Goldman (2000) and by Stanimirovic & Lazarian (2001). The question is whether the power spectrum is indeed the result of a dynamical turbulence or is merely the result of a structured static density. In the turbulence interpretation of Goldman (2000) the turbulence was generated by the tidal effects of the last close passage of the LMC about 0.2 Gyr ago. The turbulence time-scale was estimated by Goldman to be 0.4 Gyr, so the turbulence has not decayed yet. Staveley-Smith et al. (1997) observed in the SMC about five hundreds of HI super shells. Their age is more than an order of magnitude smaller than the turbulence age. Therefore, if the turbulence explanation holds, their observed radial velocities should reflect the turbulence in the gas in which they formed. In the present work we analyze the observed radial velocities of the super shells. We find that the velocities indeed manifest the statistical spatial correlations expected from turbulence. The turbulence spectrum is consistent with that obtained by Goldman (2000).

We investigate the possibility of a mass transfer enhancement during outburst in dwarf novae. We present here the first two-dimensional hydrodynamic simulations of the surface flows in the secondary, driven by the strong inhomogenous heating of the atmosphere during an outburst. We also discuss the possibility that the direct heating of the L1 point by the disc rim contributes to the mass transfer enhancement.

Detailed modelling of individual protostellar condensations is important to test the various theories. Here we present comparisons between strongly induced collapse models with one young class-0 object, IRAS4A, in the Perseus cloud and one prestellar cloud observed in the Coalsack molecular cloud.

Observations of the most distant (z≃6) QSOs in the centimetre and millimetre regime currently serve as the only direct probe of the host galaxies of these extreme systems in the Epoch of Re-ionization. Such observations reveal that about 1'3 of the hosts contain massive reservoirs of dust (>108M⊙) and molecular gas (>1010M⊙) – the fuel for galaxy formation, and also indicate coeval starbursts at a rate >103M⊙yr−1 adequate to form a large elliptical galaxy in a dynamical timescale. These data imply that a highly metal enriched, molecular ISM, can be generated in galaxies within 870 Myr of the Big Bang. High-resolution imaging of the gas also provide an estimate of the host galaxy dynamical mass. However, current observations are restricted to rare, hyper-luminous IR galaxies. I will close by considering the prospects of observing the gas, dust, and star formation in the first ‘normal’ galaxies (e.g., the Ly-α galaxies) into cosmic reionization (z>6), using ALMA and the EVLA.

We discuss education in astrometry.

We discuss some benefits and pitfalls when combining conceptually different types of closure approximations into complete Reynolds stress models of stellar convection.

Welcome to Prague. Welcome to this Congress Centre built in a close neighbourhood of the ancient seat of the first Czech dukes (Fig. 1). Its name Vyšehrad means the Upper Town. According to the oldest Czech chronicles, it was here where the legendary princess Libuše ordered her people to found the city of Prague and where she envisaged its glory touching the stars (Fig. 2). It was also here where the canon of Vyšehrad recorded in the first half of the 12th century into his chronicle some observed astronomical and meteorological phenomena.

While theoretical understanding remains to be clarified regarding the mechanisms that may or may not limit stellar masses, it is possible to empirically evaluate the existence of an upper-mass limit. ZAMS masses of the most massive stars have been estimated for a range of environments in our local Milky Way neighborhood and the Magellanic Clouds. Various statistical techniques demonstrate the existence of an upper-mass limit in this stellar sample.

The aim of the present study, based on literature data, is to find signatures of the giant radio continuum structure Loop III on the nearby interstellar medium, and search for molecular cloud and star formation, possibly triggered by its expansion. The preliminary results are as follows: (1) The 3D map of the Local Bubble, published by Lallement et al. (2003) suggests that Loop III is probably more distant than the early models had indicated. (2) The molecular clouds at high galactic latitudes in the 2nd Galactic quadrant are probably associated with the neutral/molecular wall of Loop III. (3) Star formation in Lynds 1333 and Lynds 1082 (GF 9) might have been triggered by the expansion of Loop III. (4) The supernova(e), whose explosion produced Loop III, might have been located in the SU Cas association.

We introduce an extended 3D numerical simulation study of Reynolds stress models of stellar convection and probe fluxes as well as mean temperature gradient profiles.

After discovering microquasars – active stellar systems with relativistic outflows (Mirabel et al. 1992) – many papers bringing the observational arguments on similar nature of accreting systems with different BH masses (from stellar to galactic nuclei) have appeared. It became clear that a level of activity in such systems could depend on few parameters: BH mass and angular momentum; accretion rate and magnetization parameter of accretion disk (AD); relative orientation of BH and AD angular momentum. The bolometric luminosity and characteristic variation time in such systems is proportional to BH masses, which span an interval in 5–8 decades.

A new mass model for M31 is presented. The best possible baryonic mass profile for M31 is derived from the 2MASS Ks-band image and M/L ratios from Bell et al. (2003). The best fitting rotation curve is then found within the context of ΛCDM disk galaxy formation. We find that M31 is well-described by a model that includes an adiabatically contracted halo, with an initial NFW concentration, c = 20. Models without adiabatic contraction fail to reproduce the observed rotation curve at r>15 kpc. The derived halo virial mass is Mvir = (9.4 ± 0.8) × 1011M⊙, consistent with masses derived from other observational methods.

Propagating fluctuation models can reproduce fundamental properties of the variability observed in the X-ray light curves of accreting black hole systems. We explore this type of model and show how extended emitting regions introduce at the same time energy dependent power spectral densities (PSD) and time lags between different energy bands.

The estimation of the distribution of the total (luminous and dark) mass in early type systems is hard! Even for the lucky few systems for which kinematic information is available, its implementation is mired in problems, given uncertainties about the assumptions that enter the calculations; the most critical of such assumptions involve considerations of the system geometry and the shape of its velocity ellipsoid. This work offers an independent means of getting to the mass distributions of early type galaxies, without relying directly on the phase space distribution function. The methodology is based upon the well established idea that in elliptical galaxies, the largest variations in normalised velocity dispersion profiles occur typically at R < 0.5Re (Re≡ half-light radius) and at R ≥ 2Re.

We analyze possible differences in the global environments of very metal-poor BCGs with that of typical metallicity BCGs, basing on the parameter DNN – distance to the nearest “luminous” galaxy. We find very significant difference suggesting that a higher fraction of unevolved dwarfs reside in ‘voids’.

Many galactic nuclei contain disks of gas and possibly stars surrounding a supermassive black hole. These disks may play a key role in the evolution of galactic centers. Here we address the problem of finding stable warped equilibrium configurations for such disks, considering the attraction by the black hole and the disk self-gravity as the only acting forces. We model these disks as a collection of concentric, circular rings.

We find the equilibria of such systems of rings, and determine how they scale with the ring parameters and the mass of the central black hole. We show that in some cases these disk equilibria may be highly warped. We then analyze the stability of these disks, using both direct time integration and linear stability analysis. This shows that the warped disks are stable for a range of disk-to-black hole mass ratios, when the rings extend over a limited range of radii.

The latest observational results on the formation and evolution of early-type galaxies are reviewed by focusing on the issues of mass assembly and downsizing scenario.