The evolution of stellar collision products in cluster simulations has usually been modelled using simplified prescriptions. Such prescriptions either replace the collision product with an (evolved) main sequence star, or assume that the collision product was completely mixed during the collision.

It is known from hydrodynamical simulations of stellar collisions that collision products are not completely mixed, however. We have calculated the evolution of stellar collision products and find that they are brighter than normal main sequence stars of the same mass, but not as blue as models that assume that the collision product was fully mixed during the collision.

An imperfect CTE in CCD detectors is one of the most important instrumental issues affecting both photometry and astrometry, especially in space-based observations. We discuss the CTE effect in the images taken with the Hubble Space Telescope's, Advanced Camera for Surveys in Wide Field Channel (ACS/WFC). ACS is the only imaging instrument capable of delivering sub-mas astrometry from a single observation, and it is important to take into account any instrumental systematic in positions such as the CTE effect.

This chapter lists the Adhering Organizations of the 63 National Members of the International Astronomical Union. As of September 2008, the IAU had 7 members with Interim status, 21 members in Category I, 10 members in Category II, 11 members in Category III, 3 members in Category IV, 4 members in Category V, 1 member in Category VI, 5 members in Category VII, and 1 member in Category X.

Globular Clusters provide a unique method for tracing the formation and evolution of their host galaxies. As single stellar populations they are far easier to interpret than the multi-population complexity of galaxy field stars. The scaling properties of globular clusters provide important constraints on the hierarchical assembly history of galaxies. Here we briefly review recent progress using the Hubble Space Telescope for imaging and the Keck plus Gemini telescopes for spectroscopy. We argue that the red, or metal-rich, subpopulation of GCs is associated with the bulge/spheroid component of galaxies. As one of the oldest stellar systems available for study, we discuss how globular clusters can be used to constrain the formation of galaxy bulges, in particular the role of mergers vs secular evolution. We conclude that metal-rich GCs, and hence bulges, formed very early in the Universe with more recent mergers having a small effect at most.

We propose an explanation for the origin of hyperfast neutron stars (e.g. PSR B1508+55, PSR B2224+65, RX J0822–4300) based on the hypothesis that they could be the remnants of a symmetric supernova explosion of a high-velocity massive star (or its helium core) which attained its peculiar velocity (similar to that of the neutron star) in the course of a strong three- or four-body dynamical encounter in the core of a young massive star cluster. This hypothesis implies that the dense cores of star clusters (located either in the Galactic disk or near the Galactic centre) could also produce the so-called hypervelocity stars – ordinary stars moving with a speed of ~ 1 000 km s−1.

We present the design of a Fizeau interferometer to be implemented for the GAME mission. The aim is to measure the PPN γ parameter with the same technique used for the first time by Dyson, Eddington et al., but at a 10−6 accuracy level. GAME will observe about 106 sufficiently bright stars at about 2° from the Sun. A dedicated space mission has the advantage of observing the light bending without waiting for an eclipse.

We have started a VLBI monitoring program for Asymptotic Giant Branch (AGB) stars at 22 and 43 GHz as part of a project of the VLBI Exploration of Radio Astrometry (VERA) for precisely obtaining the period-luminosity (PL) relation of Galactic Mira variables. Using accurate distances measured with VERA, we reveal PL relation in the Galaxy based on the absolute magnitudes of the sources. We selected the sources for VLBI monitoring so that they have a good coverage of various pulsation periods. Photometry in the infrared J, H, and K bands for over 600 AGB stars has also started since 2003 with the 1m telescope of Kagoshima University to obtain the pulsation periods and magnitudes. Current analysis of the phase referencing VLBI observations of S Crt shows that the parallax of 2.3±0.2 milliarcsec (mas) corresponds to a distance of 435+41−35 pc. From the infrared monitoring data, pulsation periods and magnitudes in K band for 248 sources were obtained.

We have developed a new method for post-Newtonian, high-precision integration of stellar systems containing a super-massive black hole (SMBH), splitting the forces on a particle between a dominant central force and perturbations. We used this method to perform fully collisional N-body simulations of inspiralling intermediate-mass black holes (IMBHs) in the centre of the Milky Way.

The stellar populations in the bulges of S0s, together with the galaxies' dynamics, masses and globular clusters, contain very interesting clues about their formation. I present here recent evidence suggesting that S0s are the descendants of fading spirals whose star formation ceased.

Maser emission from the SiO molecule has been widely observed in the near-circumstellar envelopes of late-type, evolved stars. VLBI images can resolve individual SiO maser spots, providing information about the kinematics and magnetic field in the extended atmospheres of these stars. This poster presents full polarization images of several SiO maser lines towards the supergiant star VY CMa. VY CMa is a particularly strong SiO maser source and allows observations of a wide range of maser transitions. We discuss implications of these observations for VY CMa morphology, polarization, and pumping models.

In this work we describe the JStuff, a preliminary generator of mock catalogues of extragalactic objects based on the Stuff code. This version is being implemented in the Java language for the ESA-Gaia satellite simulation framework. We also compare some results obtained with both versions of the simulator.

Blue stragglers stars (BSS) constitute an ubiquitous population of objects whose origin involves both dynamical and stellar evolution. We took advantage of the homogeneous sample of 56 Galactic globular clusters observed with WFPC2/HST by Piotto et al. (2002) to investigate the environmental dependence of the BSS formation mechanisms. We explore possible monovariate relations between the frequency of BSS (divided in different subsamples according to their location with respect to the parent cluster core radius and half mass radius) and the main parameters of their host GC. We also performed a Principal Component Analysis to extract the main parent cluster parameters which characterise the BSS family.

We seek to understand whether the stellar populations of galactic bulges show evidence of secular evolution triggered by the presence of the disc. To this end we re-analyse the sample of Proctor & Sansom (2002), deriving stellar population ages and element abundances from absorption line indices as functions of central velocity dispersion and Hubble type. In agreement with other studies in the literature, we find that bulges have relatively low luminosity weighted ages, the lowest age derived being 1.3 Gyr. Hence bulges are not generally old, but actually rejuvenated systems. We discuss evidence that this might be true also for the bulge of the Milky Way. The smallest bulges are the youngest with the lowest α/Fe ratios indicating the presence of significant star formation events involving 10 − 30 per cent of their total mass in the past 1 − 2 Gyr. No significant correlations of the stellar population parameters with Hubble Type are found. We show that the above relationships with σ coincide perfectly with those of early-type galaxies. At a given velocity dispersion, bulges and elliptical galaxies are indistinguishable as far as their stellar populations are concerned. These results favour an inside-out formation scenario and indicate that the discs in spiral galaxies of Hubble types Sbc and earlier cannot have a significant influence on the evolution of the stellar populations in the bulge component. The phenomenon of pseudobulge formation must be restricted to spirals of types later than Sbc.

Since 1980 variability of a sample of H2O maser sources has been monitored on the 22-metre radio telescope in Pushchino, Russia. The interval between successive observational sessions is 1–2 months. The sample includes 125 maser sources in star-forming regions (SFR) and late-type variable stars. Twenty-six-year time series of H2O line profiles have detected flares and velocity drift of spectral features. Very fast variations in the H2O maser flux (Δt ≲ 1 hour) have been detected in several SFR sources, in particular, W33B. Variations of circumstellar H2O masers in late-type stars correlate with visual light curves with a time lag of 0.3-0.4P (P is the star's period). Exceptionally strong H2O maser flares were recorded in SFR sources (Sgr B2 and others) and in the stars W Hya, R Cas and U Ori. Models for H2O maser variability are reviewed. For stellar masers shock-wave excitation of H2O line variability is discussed.

A full alphabetical list of IAU members is available online as “Supplementary data” on Cambridge Journals Online: http://www.journals.cup.org/S1743921308024435

On a daily basis the Gaia telemetry data (some 30 GB) must be stored and treated in order to reconstruct the actual observations. This initial data treatment processes all newly arrived telemetry and various pieces of auxiliary data. The first part of the process is merely a reformatting to create raw objects for permanent storage in the raw data base (some 40 TB at the end of the mission). The next part is to analyze the data to derive initial values for the observables, e.g. transit times and fluxes, producing intermediate objects. Finally, the intermediate objects are matched with sources in the data base, linking all the observations of a given source.

To check the initial data treatment algorithm we use simulations of the telemetry stream provided by GASS, the Gaia System Simulator. GASS simulates astrometric, photometric and radial velocity data, using models of the satellite and on-board instruments, as well as the models of different of objects observed by Gaia (stars, galaxies, solar system objects, . . .). On the other hand, the initial data treatment allows us to validate the data generated by GASS, which are used too to check other algorithms like the First Look or the Astrometric Global Iterative Solution (AGIS).

We have conducted an extensive photometric search for dwarf nova (DN) outbursts in 16 Galactic globular clusters (GCs). The survey was based on the rich photometric data collected by the Cluster AgeS Experiment (CASE) team. We have identified two new DNe. Together with previously known systems this gives the total number of 12 known DNe in 7 Galactic GCs. Inserting artificial light curves of “DNe” into frames of investigated clusters allowed us to assess completeness of the search. Our results clearly show that outbursting cataclysmic variables (CVs) are very rare in GCs in comparison to field CVs where half of the systems belongs to DNe. Recent X-ray observations of GCs lead to identification of hundreds of compact binaries. Many of them are promising candidates for CVs. The theory also predicts that dozens of white/red dwarf binaries should form in the cores of GCs via dynamical processes or internal evolution of the binaries. Our results rises the question about possible causes of paucity of outbursts in GCs.

We show observations obtained with the integral field spectrometer OASIS for the centers of a sample of barred galaxies. The high spatial resolution of the instrument allows to distinguish spatially some structures within these regions as defined by stellar populations of different ages and metallicities. From these data we deduce important clues about the star formation history. But we advise that, in order to obtain adequately the evolutionary sequence, a combination of chemical and synthesis models might be necessary.