The polynomial-fit method is applied to remove the uneven background of a satellite when it is near a bright primary object. Detailed analysis of this method is given. Some useful conclusions are drawn from the results of simulated data.

In this contribution we study integrated properties of dynamically segregated star clusters. The observed core radii of segregated clusters can be 50% smaller than the “true” core radius. In addition, the measured radius in the red filters is smaller than those measured in blue filters. However, these difference are small (≲10%), making it observationally challenging to detect mass segregation in extra-galactic clusters based on such a comparison. Our results follow naturally from the fact that in nearly all filters most of the light comes from the most massive stars. Therefore, the observed surface brightness profile is dominated by stars of similar mass, which are centrally concentrated and have a similar spatial distribution.

We present Gemini/IFU observations that sample the roots of the galactic wind outflows in the starburst galaxies NGC 1569 and M82. The good spatial and spectral resolutions of these observations allow us to probe the interactions of cluster winds with their environments on small scales. For both galaxies, we find a ubiquitous broad (200–300 km s−1) Hα component underlying a brighter narrower component. By mapping the properties of the individual line components, we find correlations that suggest that the broad component results from powerful cluster wind-gas clump interactions. For NGC 1569, there is little evidence for organised gas flows within the central zone and we suggest that the flow-dominated wind must form well beyond the region containing the massive star clusters. For M82, we find that the kinematics of the wind base are very complex; the width of the broad component reaches values of > 350 km s−1 at the base of the wind, and the outflow itself rapidly becomes chaotic in the inner wind region.

The damping of standing slow mode oscillations in hot (T > 6 MK) coronal loops is described in the linear limit. The effects of energy dissipation by thermal conduction, viscosity, and radiative losses and gains are examined for both stratified and nonstratified loops. We find that thermal conduction acts on the way of increasing the period of the oscillations over the sound crossing time, whereas the decay times are mostly determined by viscous dissipation. Thermal conduction alone results in slower damping of the density and velocity waves compared to the observations. Only when viscosity is added do these waves damp out at the same rate of the observed SUMER loop oscillations. In the linear limit, the periods and decay times are barely affected by gravity.

Division VIII gathers astronomers engaged in the study of the visible and invisible matter in the Universe at large, from Local Group galaxies via distant galaxies and galaxy clusters to the large-scale structure of the Universe and the cosmic background radiation.

In central regions of non-axisymmetric galaxies high-resolution hydrodynamical simulations indicate spiral shocks, which are capable of transporting gas inwards. The efficiency of transport is lower at smaller radii, therefore instead of all gas dropping onto the galactic centre, a roughly uniform distribution of high-density gas develops in the gaseous nuclear spiral downstream from the shock, and the shear in gas is very low there. These are excellent conditions for star formation. This mechanism is likely to contribute to the process of (pseudo-) bulge formation.

An exciting recent finding regarding scaling relations among globular clusters is the so-called ‘blue tilt’: clusters of the blue sub-population follow a trend of redder colour with increasing luminosity. In this contribution we estimate by means of collisional N-body simulations to which extent this trend can be explained by field star capture occurring over a Hubble time. We investigate star clusters with 103 to 106 stars. We find that the ratio between captured field stars and total number of clusters stars is very low (≲ 10−4), even for co-rotation of the star cluster in a cold disk. This holds for star clusters in the mass range of both open clusters and globular clusters. Therefore, field star capture is not a probable mechanism for creating the colour-magnitude trend of metal-poor globular clusters.

We study the relation between nuclear massive black holes and their host spheroid gravitational potential. Using AMR numerical simulations, we analyze how gas is transported into the nuclear (central kpc) regions of galaxies. We study gas fueling onto the inner accretion disk (sub-pc scale) and star formation in a massive nuclear disk like those generally found in proto-spheroids (ULIRGs, SCUBA Galaxies). These sub-pc resolution simulations of gas fueling, which is mainly depleted by star formation, naturally satisfy the ‘MBH - Mvirial’ relation, with a scatter considerably less than that observed. We find that a generalized version of the Kennicutt-Schmidt Law for starbursts is satisfied, in which the total gas depletion rate (Ṁgas = ṀBH + ṀSF) scales as Mgas/torbital.

We investigated the efficiency of planet scatterings in producing close-in planets by a direct inclusion of the dynamical tide effect into the simulations. We considered a system consists of three Jovian planets. Through a planet-planet scattering, one of the planets is sent into shorter orbit. If the eccentricity of the scattered planet is enough high, the tidal dissipation from the star makes the planetary orbit circular. We found that the short-period planets are formed at about 30% cases in our simulation and that Kozai mechanism plays an important role. In the Kozai mechanism, the high inclination obtained by planet-planet scattering is transformed to the eccentricity. It leads the pericenter of the innermost planet to approach the star close enough for tidal circularization. The formed close-in planets by this process have a widely spread inclination distribution. The degree of contribution of the process for the formation of close-in planets will be revealed by more observations of Rossiter-McLaughlin effects for transiting planets.

We examine the fate of ionizing radiation from massive stars on global scales. First, we compare the observed Hα luminosities of LMC Hii regions with those predicted by the latest generation of stellar atmosphere models. Our results imply that classical Hii regions are on average radiation-bounded, rather than density-bounded, as we found a decade ago. This is likely to necessitate an additional ionizing source for the diffuse, warm ionized medium (WIM) in galaxies. Secondly, we present new results from the SINGG Hα galaxy survey, showing that starburst galaxies have a lower fraction of WIM emission than normal star-forming galaxies. The most intriguing and consequential possible cause for this effect is the escape of ionizing radiation from starbursts. We show that the observations are also consistent with our predictions for the escape of ionizing radiation. Nevertheless, other observations do not necessarily support this scenario and other possible explanations must be considered.

High frequency acoustic waves have been suggested as a source of mechanical heating in the quiet solar chromosphere. To investigate this, we have observed intensity oscillations of several lines in the frequency interval 1.64-70mHz using data from the VTT Tenerife and the Dunn Solar Telescope at the National Solar Observatory. Our analysis of Fe i 543.45 nm, Fe i 543.29 nm and the G-band, indicate that the majority of oscillations are connected with the magnetic fields and do not provide sufficient mechanical flux for the heating of the chromosphere. This correlation is also observed in quiet Sun areas.

The VLBA is now achieving parallaxes and proper motions with accuracies approaching the micro-arcsecond domain. The apparent proper motion of Sgr A*, which reflects the orbit of the Sun around the Galactic center, has been measured with high accuracy. This measurement strongly constrains Θ0/R0 and offers a dynamical definition of the Galactic plane with Sgr A*at its origin. The intrinsic motion of Sgr A*is very small and comparable to that expected for a supermassive black hole. Trigonometric parallaxes and proper motions for a number of massive star forming regions (MSFRs) have now been measured. For almost all cases, kinematic distances exceed the true distances, suggesting that the Galactic parameters, R0 and Θ0, are inaccurate. Solutions for the Solar Motion are in general agreement with those obtained from Hipparcos data, except that MSFRs appear to be rotating slower than the Galaxy. Finally, the VLBA has been used to measure extragalactic proper motions and to map masers in distant AGN accretion disks, which will yield direct estimates of H0.

We present simultaneous observations of continuum (3.5 and 1.3cm) and water maser line emission (1.3cm) carried out with the VLA-A toward the high-mass object IRAS 23139+5939. We detected two radio continuum sources at 3.5cm separated by 0”5 (~2400 AU), I23139 and I23139S. Based on the observed continuum flux density and the spectral index, we suggest that I23139 is a thermal radio jet associated with a high-mass YSO. On the other hand, based on the spatio-kinematical distribution of the water masers, together with the continuum emission information, we speculate that I23139S is also a jet source powering some of the masers detected in the region.

Recent high-resolution simulations together with theoretical studies of the dynamical evolution of galactic disks have shown that contrary to wide-held beliefs a ‘live’, dynamically responsive, dark halo surrounding a disk does not stabilize the disk against dynamical instabilities. We generalize Toomre's Q stability parameter for a disk-halo system and show that if a disk, which would be otherwise stable, is embedded in a halo, which is too massive and cold, the combined disk-halo system can become locally Jeans unstable. The good news is, on the other hand, that this will not happen in real dark haloes, which are in radial hydrostatic equilibrium. Even very low-mass disks are not prone to such dynamical instabilities.

As far as coordination and planning of observational activities are concerned, the main need for WG-SN activities seem to lie in the field of suitable follow-ups to the many on-going and planned search programs (in particular for SNe Ia's; LOTOSS, NGSS, SNfactory, SNLS, ESSENCE, GOODS, PanStarrs, . . .). With the new robotic 2m-class telescopes (e.g., the Las Cumbres Observatory Global Telescope Network and other robotic telescopes) photometric follow-ups do not seem a major problem, but for most of the searches spectroscopic follow-up requires 4m-class telescopes at least which will become rare in the future. Possible ways out were discussed.

The members of Commission 28 on Galaxies were very busy during this General Assembly, with the Commission involved in two Symposia (IAU Symposium No. 235 Galaxy Evolution across the Hubble Time, IAU Symposium No. 238 Black Holes: from Stars to Galaxies), and two Joint Discussions (JD07 The Universe at z > 6, JD15 New Cosmology Results from the Spitzer Space Telescope). Therefore, the Business Meeting was combined with the Division VIII Business Meeting, which included a short information session on the new Commission 28 Organizing Committee. The triennial report of the Commission for 2003-2005 was also distributed, and is available on the Commission 28 web site.

The Australia Telescope Compact Array (ATCA) and the Mopra facility have been used to search for new southern class I methanol masers at 9.9, 25(J=5) and 104 GHz, which are thought to trace more energetic conditions in the interface regions of molecular outflows, than the widespread class I masers at 44 and 95 GHz. One source shows a clear outflow association.

VERA aims at astrometric observations using phase referencing VLBI techniques, whose goal is a 10 micro arc-second accuracy for annual parallax measurements. VERA has four 20-m diameter VLBI radio telescopes in Japanese archipelago with the maximum baseline length of 2,300 km. They have the two-beam observing system, which makes simultaneous observations of two objects possible. This leads to very accurate phase referencing VLBI observations. An important science goal is to make a 3-dimensional map of the Galaxy and reveal its dynamics. In order to achieve this, VERA has the 22GHz and 43GHz bands for H2O and SiO maser objects, respectively. Maser objects are compact and suitable for astrometry observations. VERA's construction was started in 2000 and the array became operational in 2004. We have already measured annual parallaxes and proper motions of some galactic objects. In the future, VERA will collaborate with Korean and Chinese VLBI stations.

Here we investigate longitudinal waves in non-isothermal hot (T ≥ 5.0 MK) coronal loops. Motivated by SOHO SUMER and Yohkoh SXT observations and taking into account gravitational stratification, thermal conduction, compressive viscosity, radiative cooling, and heating, the governing equations of 1D hydrodynamics is solved numerically for standing wave oscillations along a magnetic field line. A semicircular shape is chosen to represent a coronal loop. It was found that the decay time of standing waves decreases with the increase of the initial temperature and the periods of oscillations are affected by the different initial velocities and loop lengths studied by the numerical experiments. The predicted decay times are within the range of values inferred from Doppler-shift oscillations observed by SUMER in hot coronal loops.

There are only a few “dark galaxy” candidates discovered to date in the local Universe. One of the most prominent of them is the SW component of a merging system HI 1225+01. On the other hand, the number of known very metal-poor gas-rich dwarfs similar to I Zw 18 and SBS 0335–052 E, W has grown drastically during the last decade, from a dozen and a half to about five dozen. Many of them are very gas-rich, having from ~90 to 99% of all baryons in gas. For some of such objects that have the deep photometry data, no evidences for the light of old stars are found. At least a half of such galaxies with the prominent starbursts have various evidences of interactions, including advanced mergers. This suggests that a fraction of this group objects can be a kind of very stable protogalaxies (or “dark galaxies”), which have recently experienced strong disturbances from nearby massive galaxy-size bodies. Such a collision caused the gas instabilities and its collapse with the subsequent onset of starburst. We briefly discuss the morphology and gas kinematics for the subsample of the most metal-poor dwarfs that illustrate this picture. We discuss also the relation of these rare galaxies to the processes by which “dark galaxies” can occasionally transform to optically visible galaxies.