We have carried out observations with the Very Long Baseline Array (VLBA) to measure the parallaxes of Mira variables and are able to improve the distance estimates significantly for a fraction of our sample (U Her, S CrB and RR Aql). This is predominantly because we have enhanced our technique by making use of nearby, in-beam calibrators. Additionally, the observing conditions have improved during the current solar minimum. The distances of these stars are of fundamental importance for studying the physical properties of Asymptotic Giant Branch (AGB) stars with high mass loss.

We probe the evolution of globular clusters that could form in giant molecular clouds within high-redshift galaxies. Numerical simulations demonstrate that the large and dense enough gas clouds assemble naturally in current hierarchical models of galaxy formation. These clouds are enriched with heavy elements from earlier stars and could produce star clusters in a similar way to nearby molecular clouds. The masses and sizes of the model clusters are in excellent agreement with the observations of young massive clusters. Do these model clusters evolve into globular clusters that we see in our and external galaxies? In order to study their dynamical evolution, we calculate the orbits of model clusters using the outputs of the cosmological simulation of a Milky Way-sized galaxy. We find that at present the orbits are isotropic in the inner 50 kpc of the Galaxy and preferentially radial at larger distances. All clusters located outside 10 kpc from the center formed in the now-disrupted satellite galaxies. The spatial distribution of model clusters is spheroidal, with a power-law density profile consistent with observations. The combination of two-body scattering, tidal shocks, and stellar evolution results in the evolution of the cluster mass function from an initial power law to the observed log-normal distribution.

We evaluate the nature of bulges in the Hubble sequence, based on an analysis of 216 disk galaxies of all morphological types (S0-Sd). For this purpose we collect our various analysis made separately for early and late-type galaxies, published in a series of papers. Using the criteria by Kormendy & Kennicutt we find strong evidence of pseudobulges in all Hubble types, including S0s. However, due to the relatively massive bulges in S0-S0/a galaxies it is not probable that the (pseudo)bulges in these galaxies were formed in a similar manner as in spirals. More likely, pseudobulges particularly in strongly barred early-type disk galaxies are suggested to be a combination of star formation and the nearly exponential central components of bars.

We present a study of the globular cluster (GC) systems of nearby elliptical and S0 galaxies at a variety of wavelengths from the X-ray to the infrared. Our analysis shows that roughly half of the low mass X-ray binaries (LMXBs), that are the luminous tracers of accreting neutron star or black hole systems, are in clusters. There is a surprisingly strong correlation between the LMXB frequency and the metallicity of the GCs, with metal-rich GCs hosting three times as many LMXBs as metal-poor ones, and no convincing evidence of a correlation with GC age so far. In some of the galaxies the LMXB formation rate varies with GC color even within the red peak of the typical bimodal cluster color distribution, providing some of the strongest evidence to date that there are metallicity variations within the metal-rich GC peak as is expected in a hierarchical galaxy formation scenario. We also note that any analysis of subtler variations in GC color distributions must carefully account for both statistical and systematic errors. We caution that some published GC correlations, such as the apparent ‘blue-tilt’ or mass-metallicity effect might not have a physical origin and may be caused by systematic observational biases.

Gaia is an ESA cornerstone mission which will observe some billion stars in the galaxy enabling micro-arcsec astrometric catalogues to be constructed. In addition Gaia will produce high quality photometric and spectroscopic catalogues.

The data processing tasks are large and complex. A European consortium has been formed - the Gaia Data Processing and Analysis Consortium (DPAC). This paper describes the form of the UK Gaia Data Flow System Project contribution to the DPAC.

We have undertaken a comprehensive search for the first excited state of OH emission (J=5/2, 2Π3/2) in Planetary and Proto- Planetary Nebulae. With the Effelsberg telescope, we confirm the detection of Vy 2–2 and we present one new detection in the pPN K3−35. This detection has been confirmed by subsequent observations made at 6035 MHz with the MERLIN interferometer. This is the first detection of 6 GHz OH maser emission from a post-AGB star.

We have developped a software of Star-Image-Extractor (SIE) which works as the on-board real-time image processor. It detects and extracts only the object data from raw image data. SIE has two functions: reducing image data and providing data for the satellite's high accuracy attitude control system.

We present OH 1612 MHz maser observations towards the pre-planetary nebula OH17.7–2.0 taken with the Nançay radio telescope in 2002–2007. A bursting feature at 73 kms−1 grew by a factor of 11 in 740 days in left-hand circular polarization intensity, reaching a maximum in mid-2005. The OH flux density of features at neighbouring velocities exhibited a rise by a factor of 5–7. During the burst, the degree of circular polarization increased from 7 to 83%. The blue-shifted emission showed weak variations of 7–10% in amplitude with the exception of the bluest feature for which the OH flux decreased with the rate of ~4.4 Jy year−1. Very unusual OH outbursts of individual features and remarkable changes in the shape of the maser profile appear to be linked with recent evolutionary changes in the detached shell.

Evidence favouring a Gaussian initial mass function for systems of old globular clusters has accumulated over recent years. We show that a bell-shaped mass function may be the imprint of expulsion from protoclusters of the leftover star forming gas due to supernova activity. Owing to the corresponding weakening of its gravitational potential, a protocluster retains a fraction only of its newly formed stars. The mass fraction of bound stars extends from zero to unity depending on the star formation efficiency achieved by the protoglobular cloud. We investigate how such wide variations affect the mapping of the protoglobular cloud mass function to the initial globular cluster mass function. We conclusively demonstrate that the universality of the globular cluster mass function originates from a common protoglobular cloud mass-scale of about 106 M⊙ among galaxies. Moreover, gas removal during star formation in massive gas clouds is highlighted as the likely prime cause of the predominance of field stars in the Galactic Halo.

We present the 2D kinematics of the nuclear region of the double-nucleated low-luminosity elliptical galaxy IC 225. Observations with the GMOS-N IFU at Gemini Observatory show a large amount of metal-rich gas coincident with the off-center nucleus. However, preliminary kinematics analysis indicates that the velocity of the stars in the off-center nucleus is distinct from that of the gas at the same position. Therefore, this is an intriguing example of how the formation of a nucleus or bulge may be occurring in a low-luminosity elliptical galaxy.

We present an analysis of the radial velocities and velocity dispersions for 27 bright globular clusters in the nearby elliptical galaxy NGC 5128 (Centaurus A). For 22 clusters we combine our new velocity dispersion measurements with the information on the structural parameters, either from the literature when available or from our own data, in order to derive the cluster masses and mass-to-light (M/L) ratios. The masses range from 1.2 × 105M⊙, typical of Galactic globular clusters, to 1.4 × 107M⊙, similar to more massive dwarf globular transition objects (DGTOs) or ultra compact dwarfs (UCDs) and to nuclei of nucleated dE galaxies. The average M/LV is 3±1, larger than the average M/LV of globular clusters in the Local Group galaxies. The correlations of structural parameters, velocity dispersion, masses and M/LV for the bright globular clusters extend the properties established for the most massive Local Group clusters towards those characteristic of dwarf elliptical galaxy nuclei and DGTOs/UCDs. The detection of the mass-radius and the mass-M/LV relations for the globular clusters with masses greater than ~ 2 × 106M⊙ provides the link between “normal” old globular clusters, young massive clusters, and evolved massive objects.

JASMINE is the acronym of the Japan Astrometry Satellite Mission for INfrared (z-band: 0.9 micron) Exploration, and is planned to be launched around 2017. The main objective of JASMINE is to study the fundamental structure and evolution of the Milky Way bulge components. In order to accomplish these objectives, JASMINE will measure trigonometric parallaxes, positions and proper motions of about ten million stars in the Galactic bulge with a precision of 10 microarcsec at z = 14mag.

The primary mirror for the telescope has a diameter of 75cm with a focal length of 22.5m. The back-illuminated CCD is fabricated on a 300 micron thick substrate which is fully depleted. These thick devices have extended near infrared response. The size of the detector for z-band is 3cm×3cm with 2048×2048 pixels. The size of the field of view is about 0.6deg×0.6deg by using 64 detectors on the focal plane. The telescope is designed to have only one field of view, which is different from the designs of other astrometric satellites. JASMINE will observe overlapping fields without gaps to survey a total area of about 20deg×10 deg around the Galactic bulge. Accordingly we make a “large frame” of 20deg×10 deg by linking the small frames using stars in overlapping regions. JASMINE will observe the Galactic bulge repeatedly during the mission life of about 5 years.

We present extensive photometric and spectroscopic study to give a new insight in the bulge stellar population. Super-solar α/Fe and its constant value along the radial profile, in most of the galaxies, suggest that the star formation in these objects has been fast and occurred at the same time in the whole bulge.

Astrometric observations with the VLBA with accuracies approaching ~ 10 μas are being conducted in order to better understand the Galaxy. The location of Sgr A* on infrared images can be determined with an accuracy of a few mas, using stars with SiO maser emission as a calibration grid for infrared images. The apparent proper motion of Sgr A*, which is dominated by the effects of the orbit of the Sun around the Galactic center, has been measured with high accuracy. This measurement strongly constrains Θ0R0 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. When combined with infrared results, this provides overwhelming evidence that Sgr A* is a supermassive black hole. Finally, we are engaged in a large project to map the spiral structure and kinematics of the Galaxy. Preliminary trigonometric parallaxes, obtained with the VLBA, to eight massive star forming regions are presented.

I have analyzed the radial velocities in two large samples of maser stars that cover the Galactic plane from l = +40deg to l = −40deg through the Galactic Centre. I compare a diagram of longitude versus radial velocity as observed with a diagram obtained from the calculation of orbits in a simple, but realistic potential containing a weak, rotating bar. Almost all stars belong to the Galactic disk but there is a small sample with high velocities close to the Galactic Centre and in the so-called forbidden quadrants. These velocities cannot be explained by a combination of pure Galactic rotation and a modest dispersion in velocity. An acceptable explanation is one in which the stars of this small sample move up and down a rotating Galactic bar.

The evolution induced by dynamical friction on a spherical shell of rigid satellites interacting directly with the particles sampling the host elliptical galaxy is followed by means of N-body simulations for a variety of shell–galaxy configurations.

We have started a long term project to analyse the role played by bars in bulge formation and the formation and evolution of bars from the point of view of their star formation histories and stellar populations. To this aim, we have obtained high S/N long slit spectra of 22 barred galaxies, ranging in morphological types between S0 to Sb galaxies. We have obtained Lick/IDS indices along the bar for all the sample galaxies. We used Vazdekis et al. (2007) models to derive simple stellar population ages and metallicities. Extreme care has been taken to correct the indices for any nebular contribution. Preliminary results show that the bulges of barred galaxies are similar to those of unbarred galaxies. The metalicity gradients along bars show a dependency with the central stellar velocity dispersion. The galaxies with higher central dispersion appear to have a gradient in both age and metallicity changing radially outward to a younger and more metal rich population. The galaxies with lower central velocity dispersion show a change in age and metallicity with respect to the inner part of the bar with the populations at the end of the bar being younger or same age and more metal poor. There is no correlation between the gradient and the morphological or nuclear type. There is no correlation either with the total K-band luminosity. The fact that we observe galaxies with the outer parts of the bar more metal rich than the inner parts shows that at least some bars are old, since it requires long time for the observed enrichment to take place. The gradients in these bars are opposite to what is generally found in disks. The correlation between the central velocity dispersion and the bar gradient relates both, the dynamical and stellar population aging of the bar.

To advance from milli-arcsecond to micro-arcsecond astrometry, time keeping capability and its comparison among different stations need to be improved and enhanced. The T2L2 (Time transfer by laser link) experiment under development at OCA and CNES to be launched in 2008 on Jason-2, allows the synchronization of remote clocks on Earth. It is based on the propagation of light pulses in space which is better controlled than propagation of radio waves. In this paper, characteristics are presented for both a common view and non-common view T2L2 comparisons of clocks between China and France.

The Milky Way is the only galaxy for which we can resolve individual stars at all evolutionary phases, from the Galactic center to the outskirt. The last decade, thanks to the advent of near IR detectors and 8 meter class telescopes, has seen a great progress in the understanding of the Milky Way central region: the bulge. Here we review the most recent results regarding the bulge structure, age, kinematics and chemical composition. These results have profound implications for the formation and evolution of the Milky Way and of galaxies in general. This paper provides a summary on our current understanding of the Milky Way bulge, intended mainly for workers on other fields.

We present results from a new wide-field study of the NGC 5128 globular cluster system. We have obtained new high resolution images with the Magellan 6.4m + IMACS camera. Our images cover an area of 1.2x1.2 sq. degrees and have a seeing of 0.45″. This allows us to not only resolve most of the globular clusters (GCs) but also derive their structural parameters. These are combined with existing Washington photometry in order to select by metallicity. We present here results for a subsample of 359 GCs which includes all currently confirmed GC members of the system. Our derived sizes are in very good agreement with those derived from ACS data. We find, as expected, that the metal-rich GCs in the inner regions (r < 10′) are 26% smaller than their metal-poor components, but in the outer region this normal trend is reversed. We compare our GCs to previous results for GCs, UCDs, etc. in the luminosity - size plane and find substantial overlap between different types of objects, indicating more of a continuum in these properties.