In the daily RATAN-600 monitoring of the radio variability of the microquasar GRS1915+105 we detected a clear correlation of the flaring radio emission and X-rays “spikes” at 2–12 keV emission (1–2 Crab) detected with RXTE (ASM data) during nine bright (200–600 mJy) radio flares in October 2005. The spectra of these flares in maximum were optically thick at ν<2.3 GHz and optically thin at ν≥2.3 GHz. During radio flares the spectra of the X-ray spikes became definitely softer than those of a quiescent radio state. Thus these data indicated transitions from very high/hard states to high/soft ones during which massive ejections are probably happened, and the ejections are detected as the radio flares.

The degree to which outer dark matter halos of spiral galaxies rotate with the disk is sensitive to their accretion history and may be probed with associated satellite galaxies. We use the Steward Observatory Bok telescope to measure the sense of rotation of nearby isolated spirals and combine these data with those of their associated satellites (drawn from SDSS) to directly test predictions from numerical simulations. We aim to constrain models of galaxy formation by measuring the projected component of the halo angular momentum that is aligned with that of spiral galaxy disks, Jz. We find the mean bulk rotation of the ensemble satellite system to be co-rotating with the disk with a velocity of 22 ± 13 km/s, in general agreement with previous observational studies and suggesting that galaxy disks could be formed by halo baryons collapsing by a factor of ≈10. We also find a prograde satellite fraction of 51% and Jz, of the satellite system to be positively correlated with the disk, albeit at low significance (2655 ± 2232 kpc km/s).

Virtual Observatory (VO) is an emerging astronomical infrastructure for sharing the astronomical data set in the world. National Astronomical Observatory of Japan (NAOJ) started its VO project (Japanese Virtual Observatory – JVO) in 2002, and developed JVO portal prototypes. We have carried out several science use cases, such as cosmic string searches and QSO environment studies, by using the prototype system to examine the functionality of the system. This paper describes a preliminary result of the latter science use case.

We perform Monte Carlo calculation to determine the radiation spectra from magnetized, low angular momentum accretion flow. Magneto-hydrodynamical simulation (with angular momentum parameter lambda of about 2 Rg c) was performed by Proga & Begelman 2003. Because simulation neglect radiative cooling, we compute electron temperature separately, including ohmic heating, parametrized with small δ coefficient, ion-electron coupling, radiative cooling and advection. Radiation spectra are obtained taking into account, thermal synchrotron and bremsstrahlung radiation, self absorption and Comptonization processes.

We show which parts of the flow are responsible for characteristic spectral features and how the spectrum changes in different accretion states. We compare our results with Galactic Center black hole radiation spectra, where low angular momentum accretion is suggested. Accretion state changes seems to be a promising model for the flaring behavior of Galactic Center black hole. We also show the radiation intensity maps in radio and X-rays energy band for viewing angle i = 90°.

We have analyzed the level and type of nuclear activity in 720 galaxies belonging to a large complete sample of Compact Groups (UZC-CGs). We have found that most (67%) galaxies show emission lines and that the most frequent (43%) nuclear activity is AGN. AGNs are mainly hosted in bright early type galaxies and early spirals, at variance with HII which reside in late spirals of lower luminosity. CGs which have a dominant content of AGNs and TOs have larger σv and lower Rp than CGs dominated by HII.

The total masses of binaries are calculated on the basis of their orbital elements from the Sixth Catalog of Orbits of Visual Binary Stars. They are then compared with the values resulted from the mass-luminosity relation for the Main Sequence where as the input data are used: trigonometric parallax, total apparent magnitude of the pair (source Hipparcos Catalogue) and magnitude difference (source Hipparcos Catalogue and Photometric Magnitude Difference Catalog). It seems that for the pairs indicated as having qualitative orbital elements the agreement between the total-mass values obtained in these two ways is satisfactory.

Accretion at rates exceeding the Eddington limit is common in close binaries. I summarize the arguments leading to the conclusion that such stellar–mass systems appear as ultraluminous X-ray sources when viewed close the the inner accretion disc axis, and like SS433 when viewed from other angles.

I show that AGN are unlikely to achieve electron–scattering Eddington ratios as high as ULXs, so there are few ULX analogues among quasars. However hyperaccretion of dusty matter is common among AGN. The resulting outflow naturally has a toroidal geometry, and may well be the origin of the dusty torus invoked in unified AGN schemes.

As young stars form, they interact with their environment in many ways. We study the radiative interaction of a young star with its surrounding cluster environment. The change in gas temperature caused by a forming star can trigger the formation or inhibit the growth of nearby star forming cores. We calculate the gas temperature around a single star by balancing the dust-gas collisional heating, molecular cooling, and cosmic ray heating rates for a grid of models with various luminosities and density distributions. In the future, this work can be used in large-scale simulations of clustered star formation to study the effect of using a gas temperature which depends not only on density, but also on radiative environment.

Studying the chemical compositions and color-magnitude diagrams of globular clusters in the nearby low-mass galaxies is critical to compare properties of these long-living objects situated in galaxies of different type and mass, and to establish the role of dwarf galaxies as building blocks of massive early-type and spiral galaxies. We present measurements of ages, metallicities and [α/Fe] ratios for 16 globular clusters (GC) in NGC147, NGC185, and NGC205 and for the central regions of the diffuse galaxy light in NGC185, and NGC205, based on measurements of absorption line indices as defined by the Lick standard system in spectra obtained with the SCORPIO multi-slit spectrograph at the 6-m telescope of the Russian Academy of Sciences. We include in our analysis high-quality HST/WFPC2 photometry of individual stars in the GGs to investigate the influence of their horizontal branch (HB) morphology on the spectroscopic analysis. The HB morphologies for our sample GCs follow the same behavior with metallicity as younger halo Galactic globular clusters. We show that it is unlikely that they bias our spectroscopic age estimates based on Balmer absorption-line indices. Almost all our sample GCs appear to be old (T > 8 Gyr) and metal-poor ([Z/H]<−1.1). We find that most of the GCs in the studied galaxies are weakly or not α-enhanced, in contrast to the population of GCs in nearby early-type galaxies, and to the halo population of GCs in M31 and Milky Way.

With relatively low funds, the Departamento de Astronomía de la Universidad de Guanajuato, in Mexico, has successfully carried out the modernization of a rustic astronomical observatory. At this site, once it is fully refurbished, it is planned to hold not only public observations, but also to have an ambitious programme of science popularization devoted to scholars.

This article was co-authored by all invited speakers at Joint Discussion 6 on Neutron Stars and Black Holes in Star Clusters, which took place during the IAU General Assembly in Prague, Czech Republic, on August 17 and 18, 2006. Each section presents a short summary of recent developments in a key area of research, incorporating the main ideas expressed during the corresponding panel discussion at the meeting.

Observations give tight constraints on the temporal and spatial scales of particle heating in solar flares, and on the required efficiency. Electrons are accelerated into a quasi-thermal population of a few tens of keV. X- and γ-rays imply tails in electron and ion distributions reaching tens of MeV and above. Simple estimates indicate that all available electrons are accelerated at least once to moderate energies, pointing to an initial process resembling bulk heating rather than acceleration of a small or localized population. In the absence of effective collisions, wave-particle interactions are the prime candidate. Here we address the outstanding questions, (i) what process can heat the entire reconnecting plasma to the above energies, and (ii) what provides the free energy for wave-particle interactions? We propose a process in which initially the ions are heated and provide the free energy for electron heating and tail formation.

We investigate the near-infrared K-band evolution of early-type galaxies in the cluster of galaxies Abell2390 at z = 0.23. Using the Omega-Prime camera at the 3.5-m Calar Alto telescope deep imaging (texp = 53 min) over a 6' × 6' field has been obtained. The measured K-band magnitudes of 28 galaxies are combined with the spectroscopic and morphological data of Fritz et al. (2005) to construct the Faber-Jackson and Fundamental Plane relations in the NIR. By comparing our distant galaxies to a local sample of cluster ellipticals (Pahre 1999), we find on average a mild luminosity evolution for both scaling relations (ΔMK ~ 0.6 − 0.7 mag) compatible with passive evolution of the stellar populations.

Simulating disk galaxies within the current paradigm of galaxy formation has been a long standing problem. In comparison with observations, the simulated disks were too small and too centrally concentrated, due to a large loss of angular momentum during formation. This is known as the angular momentum catastrophe (Navarro & Benz (1991)). Recently, some progress has been made in reducing this effect by changing the cosmology, including various feedback mechanisms, improving numerical resolution and carefully selecting initial conditions with a quiet merging history after z≈2. Unfortunately, it remains unclear which of these effects, or which combination, has resulted in more realistic disk formation. In order to address this problem, we conduct a systematical study using the N-body code GADGET2 (Springel (2005)). We adopt a flat ΛCDM cosmology with Ωm=0.3, ΩΛ=0.7, Ωbar=0.04 and h=0.65. Using a softening of 0.5 kpc we find disks with a very compact unresolved gas clump in the center and a thin, extended disk (R≈10kpc) of very low mass around it.

In this invited contribution I review the justifications for the attempts, currently very popular, to include in semi-analytic models of galaxy formation prescriptions to describe the mutual link between the star formation and nuclear activity in galaxies, which has been for surprisingly long time neglected.

The majority of normal disk galaxies are characterized by non-axisymmetric structures like spirals or bars. These structural elements have been widely discussed in the literature as a result of gravitational instabilities which are connected to growing density waves or global instabilities of disks. A first insight into the properties of galactic discs was provided by linear stability analysis. However, a disadvantage of linear stability analysis remained its restriction to small perturbations, both in amplitude and wavelength. Thus, numerical simulations, especially hydrodynamical and stellar-hydrodynamical simulations became a primary tool for the analysis of galactic evolution.

Motivated by the GALEX discovery of recent star formation in outermost regions of M83 and NGC4625, we have investigated the nature of the XUV disks with follow-up high resolution imaging and spectroscopy, and attempted to detect them at other wavelengths (IR, Hα). We searched for additional XUV-disk galaxies in the local universe, in order to quantify the incidence of the XUV-disk phenomenon, infer the causes of such extended star formation (SF), and place these systems in the context of disk galaxy evolution.

Chandra and XMM, offering between them high angular resolution, substantial collecting area, and spatially-resolved spectroscopy at good spectral resolution, have given us the means to discover hitherto unanticipated phenomena, in groups as in clusters, and to explore a new set of issues that bring us closer to understanding the formation and evolution of groups and their constituent galaxies: the distribution of heavy elements, the presence of X-ray cavities and their relation to radio observations, the nature of cooling cores, and X-ray signatures of recent galaxy interactions. We here show Chandra and XMM data selected to illustrate recent results regarding some of these themes.

The Kepler Mission is a space-based photometric mission with a differential photometric precision of 14 ppm (at V = 12 for a 6.5 hour transit). It is designed to continuously observe a single field of view (FOV) of greater then 100 square degrees in the Cygnus-Lyra region for four or more years. The primary goal of the mission is to monitor more than one-hundred thousand stars for transits of Earth-size and smaller planets in the habitable zone of solar-like stars. In the process, many eclipsing binaries (EB) will also be detected and light curves produced. To enhance and optimize the mission results, the stellar characteristics for all the stars in the Kepler FOV with V < 16 will have been determined prior to launch. As part of the verification process, stars with transit candidates will have radial-velocity follow-up observations performed to determine the component masses and thereby separate eclipses caused by stellar companions from transits caused by planets. The result will be a rich database on EBs. The community will have access to the archive for further analysis, such as, for EB modeling of the high-precision light curves. A guest observer program is also planned to allow for photometric observations of objects not on the target list but within the FOV.

The critical property of the black hole is the presence of the event horizon. It may be detected only by means of the detailed study of the emission features of its surroundings. The temporal resolution of such observations has to be better than ∼ rg/c, and it lies in the 10−6–10s range depending on the black hole mass. In SAO RAS we have developed the MANIA hardware and software complex based on the panoramic photon counter and use it in observations on 6m telescope for the search and investigation of the optical variability on the time scales of 106–103 s of various astronomical objects. We present the hardware and methods used for these photometrical, spectroscopic and polarimetrical observations, the principles and criteria of the object selection. The list of the latter includes objects with featureless optical spectra (DC white dwarfs, blazars) and long microlensing events.

We present the results of the observations of two objects-candidates – long MACHO event MACHO-1999-BLG-22 and radio-loud x-ray source with featureless optical spectrum J1942+10 – on the 6-m telescope in June-July 2006.