We study fossil galaxy groups, their hot gas and the galaxy properties. Fossils are more X-ray luminous than non-fossil groups, however, they fall comfortably on the conventional L-T relation of galaxy groups and clusters indicating that their X-ray luminosity and temperature are both boosted, arguably, as a result of their early formation. The central dominant galaxy in fossils have optical luminosity comparable to the brightest cluster galaxies (BCGs), however, the isophotal shapes of the central galaxy in fossils are non-boxy in contrast to the isophotes of majority of the BCGs.

It is known that most of stars are formed as clusters (Lada & Lada 2003, ARAA 41, L57) and clusters are formed by triggering. However, the relationships of molecular clouds' conditions and properties of formed stars by triggering is not well studied. To clarify differences between triggered and spontaneous star formation through physical properties of molecular clouds (e.g. mass, density, morphology), we observed the W5-East HII region. The W5-East HII region is located at 2 kpc and has a 10 pc extent of HII region. This region has 3 Bright Rimmed Clouds (BRCs; Sugitani et al. 1991, ApJS 77, S59), which are interface between HII regions and molecular clouds, and known as sites of triggered star formation. The molecular clouds surround the W5-East (Karr et al. 2003, ApJ, 595, 900), thus we expect molecular clouds morphology is affected by the HII region and the cloud evolution is supposed to be dominated by the expanding HII region.

With the advent in the near future of radio telescopes such as LOFAR and the SKA, a new window on the high-redshift Universe will be opened. In particular, it will be possible, for the first time, to observe the 21-cm signal from the diffuse IGM prior to its complete re-ionization and thus probe the ‘dark ages’. I discuss the theoretical modelling of the re-ionization process and its observability through the 21-cm signal and the CMB anisotropies.

A pinhole camera has the advantage of undistorted field of view. Its imaging capability is limited by random (diffraction and atmospheric seeing) and systematic (penumbra) effects. The Pinhole Solar Monitor, PSM, measures the solar angular diameter by timing meridian transits. Meridian transits have been videorecorded with UTC synchronization at the pinhole gnomon of Santa Maria degli Angeli church in Rome. The tarature of this Clementine Gnomon is outlined with its accuracy as PSM. On the Moon an array of such PSM equipped with 1000 lines for parallel transits can monitor 0.1” variations of solar diameter.

We examine observational properties of relativistic black hole winds as an origin of high luminosity sources such as microquasars and ultra-luminous X-ray sources (ULXs). When strong relativistic wind/outflow happens in the vicinity of the black hole, the wind might form the optically-thick photosphere. Therefore the emission observed in ULXs might come from the photosphere of the wind, not from the accretion disk.

We found that the location of the photosphere is larger than the disk thickness for super-Eddington mass-outflow rates and sub-relativistic wind velocities (v ∼ 0.1–0.2 c). To understand the radiative structure in the high luminosity sources, we should take into account not only the emission from the accretion disk but also the emission from the outflow at the same time.

We present a detailed study of stellar line indices along the bar region for a sample of six early-type galaxies. We find positive gradients within the bar region in the metal indices in four of the six galaxies, and opposite trends in the other two. These latter two galaxies are classified as SAB and they present exponential bar light profiles. For all the galaxies, we find a positive gradient in the Balmer indices. There is a clear correlation between the position of morphological features inside the bar region with changes in the slope and value of the indices, which indicate, using stellar population analysis, changes in the stellar population. Therefore, it seems that the bar regions show a gradient in both age and metallicity, changing radially to younger and more metal rich populations for all the galaxies except for those two with exponential profiles. This is the first time such an analysis of the stellar populations in bars has been performed. The radial distribution of the indices is related to the star formation history of the bar, understanding these trends will help us to understand how bars are formed and how they evolve.

We report on our studies of the physical structure of the planetary nebula (PN) NGC 7662. Using (3D) Integral Field Spectroscopy we have been able to measure the electron temperature more accurately and at a larger number of radial locations than before. Here we briefly present our method by which we find a strong positive temperature gradient with increasing radius. According to hydrodynamic models a hot halo, when compared to the central star, can be the product of the passage of an ionization front (e.g. Marten 1993). Such a gradient is not found in equilibrium models, and this finding – when confirmed for other objects – strongly advocates the use of hydrodynamic models when modeling PN halos.

We present a systematic study of the properties of the narrow-line region (NLR) of narrow-line Seyfert 1 galaxies (NLS1s) using Sloan Digital Sky Survey (SDSS) spectroscopy. Various correlations between the observed parameters and physical properties of NLS1s and broad-line Seyfert 1 galaxies (BLS1s) are detected. We search for possible origins of these trends by employing correlation analyses. We further investigate the relationship between black hole mass, Eddington ratio (L/LEdd) and physical parameters of the NLR.

Radio galaxies are identified with the most massive host galaxies known out to z = 5 and can put strong constraints on galaxy evolution models, provided their space density is accurately determined. Here, I present the important role low-frequency radio surveys will have in this by selecting the highest redshift radio galaxies using the steepness of their radio spectra.

One of the observational facts about sunspots is that magnetic field strength of sunspots varies in narrow interval $\approx$ from 1 to 4–5 kG. Why sunspot equilibrium is stable only under these values? To answer this question, we propose the energetic model of sunspot, which involves the gravitational energy of the system. Formation of a sunspot is followed by redistribution of gas density along the vertical: cooled plasma flows down, inside the “magnetic funnel”, from above the sunspot to the “low boundary of magnetic flux tube”, i.e. to the region where the magnetic field of sunspot decreases abruptly with depth. Theoretical model gives the interval of stable sunspot equilibria exactly between 0.8–1.0 and 4–6 kG, which suites the observations. The “depth of sunspot” turns to be about 2–4 Mm – this fact now is approved by helioseismology. Also, the long-term (T$\,{>}\,$20 min) eigen oscillations of sunspot, as a whole, are studied. These oscillations were measured by different methods, being observed as quasi periodical vertical displacements of the body of sunspot followed by variations of its radius and magnetic field strength.

We present the latest results from our study of PNe and HII regions in two Local Group dwarf irregular galaxies IC 10 and NGC 6822.

Recent observations have revealed a class of unusually HI-rich early-type galaxies. By combining observations of their morphology, stellar populations and neutral hydrogen we aim to understand how these galaxies fit into the hierarchical formation paradigm. Here we present the result of our radio and optical observations of a test case galaxy, the E/S0 IC 4200.

HST multi-epoch images and VLT integral-field, high resolution spectroscopy allowed us a robust determination of the 3-D geometry and orientation of the nebula surrounding He 2-147, and to measure its apparent expansion in the plane of the sky. Applying the expansion parallax method results in a distance which is significantly shorter that the one obtained via the period-luminosity (P-L) relationship for the Mira component. We show how allowing for shock excitation of the nebula, as suggested by the extremely broad nebular line profiles, enables both distance derivations to be reconciled.

We construct a model of the physical structure of photoevaporating protoplanetary disks, and numerically calculate the coagulation and settling/evaporating process of dust particles in the disks. Our result show that (sub)micron-sized-dust-particles could evaporate with the gas, which leads to dispersal of infrared excess radiation from the disks.

We have made a detailed model of the physical structure of protoplanetary disks, taking into account X-ray and ultraviolet (UV) irradiation from a central star, as well as dust size growth and settling towards the disk midplane. Also, we calculate the level populations and line emission of molecular hydrogen from the disks, which shows that the dust evolution changes the physical properties of the disk, and then the line ratios of the molecular hydrogen emission.

We present some preliminary results obtained within the MAGPOP-ITP collaboration for a subsample of four dwarf elliptical galaxies. On the basis of high-resolution, optical spectroscopic data obtained for these galaxies at the WHT, their ages, metallicities and single element abundance ratios have been derived from their line-strength indices and the improved, MILES-based, stellar population model predictions by Vazdekis et al. (in preparation).

We present a systematic investigation of the velocity fields of both isolated and interacting spiral galaxies in combined N-body/hydrodynamical simulations. Closely mimicking the procedures applied in observations of distant, small, and faint galaxies we extract rotation curves (RCs) and compare the results of the simulation directly to observations. Irregularities in the velocity field reflect disturbances in the gravitational potential of the galaxy. They can be used to trace the recent interaction history of a galaxy and give possible clues to the type of the respective interaction. In addition, identifying disturbances in the RCs is important for Tully-Fisher studies in order to accurately derive the maximum rotation velocity.

A new assessment of the physics of the luminosity function of planetary nebulae is presented, based on our grid of nebular evolutionary sequences computed with a 1D radiation-hydrodynamics code. The nebular evolution is followed from the formation stage in the vicinity of the asymptotic-giant branch across the Hertzsprung-Russell diagram until the white-dwarf domain is reached, for various central-star models coupled to different initial envelope configurations. Along each sequence the relevant line luminosities of the nebulae are computed and analyzed. Our models predict that reasonably dense initial circumstellar envelopes with central stars of slightly above 0.6 $M$_{\odot}$$ will remain nearly optically thick and are able to provide the observed 5007 Å cutoff luminosity. We cannot support the claim of Marigo et al. (2004) according to which only planetary nebulae with central stars of $> 0.7$$M_{\odot}$ are able to provide sufficient 5007 Å line emission to account for the bright end of the luminosity function.

We have observed the Spitzer extragalactic First Look Survey (xFLS) region with the Giant Meterwave Radio Telescope (GMRT), near Pune, India, at 610 MHz. Seven pointings were observed with the GMRT, one central and six in a surrounding hexagon. Each field was observed with an integration time of ~ 200 min., in a series of scans spread over a range of LST to improve u – v coverage. Two sidebands, each of 16 MHz with 128 channels – to allow narrow band interference to be excised efficiently – were observed. The synthesised beam of the images is ~ 5″ and as the primary beam of the GMRT at 610 MHz is ~ 43′, these seven pointings cover most of the xFLS region.

Recent X-ray observations of microquasars and Seyfert galaxies reveal broad emission lines in their spectra, which can arise in the innermost parts of accretion disks. Recently Müller & Camenzind (2004) classified different types of spectral line shapes and described their origin. Zakharov (2006b) clarified their conclusions about an origin of doubled peaked and double horned line shapes in the framework of a radiating annulus model and discussed s possibility to evaluate black hole parameters analyzing spectral line shapes.