We study the metal abundances of F and G type stars in the Galactic disk and halo using the Canada–France–Hawaii Telescope Legacy Survey D4 field. For a sample of stars within 7 kpc of the Galactic plane, we derive mean abundance values of [Fe/H] = −0.77 ± 0.36 dex for the thick disk, and [Fe/H] = –1.42 ± 0.98 dex for the stellar halo, respectively. These metallicites are consistent with the metallicity estimates from the Sloan Digital Sky Survey Data Release 6. We do not find a vertical abundance gradient for the thick disk between 1 kpc and 4 kpc. However, stars within 1 kpc of the Galactic plane are saturated in our dataset, and therefore we cannot rule out the observed vertical metallicity gradient for the thick disk stars in the SDSS. Moreover, we find a negative trend in the halo metallicity with increasing distance from the Galactic plane. This trend could be due to a contribution from an increasing number of very metal poor stars that belong to the outer halo. However, systematic effects in photometric metallicities are largest for the most metal poor stars, and therefore these effects cannot be ruled out.

The results of 21 cm HI survey observations are presented for two fields, centred on the Centaurus and Fornax southern galaxy clusters. One previously uncatalogued dwarf galaxy was detected near the southern edge of the Fornax cluster, and is visible on UKST survey plates. Implications for the Parkes Multibeam All Sky Survey are discussed.

The long term goal of large-scale chemical tagging is to use stellar elemental abundances as a tracer of dispersed substructures of the Galactic disk. The identification of such lost stellar aggregates and the exploration of their chemical properties will be key in understanding the formation and evolution of the disk. Present day stellar structures such as open clusters and moving groups are the ideal testing grounds for the viability of chemical tagging, as they are believed to be the remnants of the original larger star-forming aggregates. Until recently, high accuracy elemental abundance studies of open clusters and moving groups having been lacking in the literature. In this paper we examine recent high resolution abundance studies of open clusters to explore the various abundance trends and reasses the prospects of large-scale chemical tagging.

We have monitored multi-TeV cosmic rays by a small air shower array in Tehran (35°43′ N, 51°20′ E, 1200 m = 890 g cm−2). More than 1.1 × 106 extensive air shower events were recorded. These observations enabled us to analyse sidereal variation of the galactic cosmic ray intensity. The observed sidereal daily variation is compared to the expected variation which includes the Compton–Getting effect due to the motion of the earth in the Galaxy. In addition to the Compton–Getting effect, an anisotropy has been observed which is due to a unidirectional anisotropy of cosmic ray flow along the Galactic arms.

We evaluated new colour transformations for the Sloan photometry by 224 standards and used them to revise both the equations for photometric parallax estimation and metallicity calibration cited by Karaali et al. (2003). This process improves the metallicity and absolute magnitude estimations by [Fe/H] ≤ 0.3 dex and M g′ H ≥ 0.1 mag respectively. There is a high correlation for metallicities and absolute magnitudes derived for two systems, UBV and Sloan, by means of the revised calibrations.

We present computations of nucleosynthesis in red giants and Asymptotic Giant Branch (AGB) stars of Population I experiencing extended mixing. The assumed physical cause for mass transport is the buoyancy of magnetized structures, according to recent suggestions. The peculiar property of such a mechanism is to allow for both fast and slow mixing phenomena, as required for reproducing the spread in Li abundances displayed by red giants and as discussed in an accompanying paper. We explore here the effects of this kind of mass transport on CNO and intermediate-mass nuclei and compare the results with the available evidence from evolved red giants and from the isotopic composition of presolar grains of AGB origin. It is found that a good general accord exists between predictions and measurements; in this framework we also show which type of observational data best constrains the various parameters. We conclude that magnetic buoyancy, allowing for mixing at rather different speeds, can be an interesting scenario to explore for explaining together the abundances of CNO nuclei and of Li.

A large scale 12CO J = 1 → 0 molecular line map of the Carina molecular cloud complex was obtained with the Mopra radio telescope in order to investigate its spatial and kinematic structure. The data show a complex velocity structure in two distinct cloud regions — the Northern and Southern Carina clouds. Two different clump identification methods (GAUSSCLUMPS and CLUMPFIND) were applied to the data. Though both algorithms find a similar clump mass spectral index (1.95 and 1.8, respectively), the properties of the clumps (mass, size, virial equilibrium) differ significantly. We discuss possible explanations for this discrepancy and question the validity of the Larson relations which could be an artifact of the limited spatial resolution and dynamic range of the observations.

We report here on extragalactic large-scale structures uncovered by a deep optical survey for galaxies behind the southern Milky Way. Systematic visual inspection of the ESO/SRC survey revealed over 10000 previously unknown galaxies in the region 265° ≲ l ≲ 340°, ∣b∣ ≲ 10°. With subsequently obtained redshifts of more than 10% of these galaxies, new structures across the Milky Way are unveiled, such as a filament at ∼2500 km s−1 connecting to the Hydra and Antlia clusters, a shallow extended superduster in Vela (∼6000 km s−1), and a nearby (4882 km s−1), very massive (M ∼ 2 – 5 × 1015 M ☉), rich Coma-like cluster which seems to constitute the previously unidentified centre of the Great Attractor.

The innermost part of the Milky Way, where the foreground obscuration in the blue is AB ≳ 5m, i.e. where HI-column densities N hi ≳ 6·1021cm−2, remains fully opaque. In this approximately 8° wide strip, the forthcoming blind HI survey with the multibeam system at Parkes will provide the only tool to unveil this part of the extragalactic sky.

We developed a chemical code within gadget2 which allows the description of the enrichment of the Universe as a function of redshift, taking into account detailed metal production by supernovae Ia and II, and metal-dependent cooling. This is the first numerical code that includes both chemical production and metal-dependent cooling in a cosmological context. By analysing the cosmic star formation rate, we found that the effects of considering a metal-dependent cooling are important, principally, for z ≤ 3. In simulations where primordial cooling functions are used, the comoving star formation rate could be up to 20%; lower than those obtained in runs with metal-dependent cooling functions. Within galaxy-like objects, the presence of chemical elements changes the star-formation rates and, consequently, the chemical production and patterns of stars. However, owing to non-linear evolution of the structure, the effects depend on the evolutionary history path of each galaxy-like object.

We present new results on the evolution and nucleosynthesis in rotating AGB stars. We analyse the role of the gradient of mean molecular weight in the mixing process and show that neglecting this component induces a potentially strong third dredge-up. We also quantify the impact of rotation on the structure and conclude that the effects of rotation (1) mainly concern the inner, fast rotating regions of the stars and (2) are relatively weak as long as rotational mixing does not induce a deep third dredge-up. We also focus our investigations on the s-process nucleosynthesis and show that rotational mixing tends to inhibit the production of s-elements. This results from the contamination of the 13C-rich layers responsible for the neutron production by the poisonous 14N. Our calculations also indicate that the distribution of s-process elements depends sensitively on the magnitude of the diffusion coefficient. These results suggest that rotational mixing is not the main mechanism responsible for the production of s-elements in AGB stars, but that it can influence, and in particular reduce, the final enrichment in s-elements.

This paper presents the initial results of a multi-site photometric programme to examine the extraordinary behaviour displayed by 18 R Coronae Borealis (RCB) stars in the Magellanic Clouds (MCs). RCB stars exhibit a unique variability whereby they undergo rapid declines of up to several magnitudes. These are thought to be caused by the formation of dust in the stellar environment which reduces the brightness. The monitoring programme comprised the collection of UBVRI photometric data using five telescopes located at three different southern hemisphere longitudes (Las Campanas Observatory in Chile, Mount John University Observatory in New Zealand, and the Southern African Large Telescope, SALT, in South Africa). Examination of the data acquired in the V and I filters resulted in the identification of a total of 18 RCB declines occurring in four stars. Construction of colour–magnitude diagrams (V versus V – I), during the recovery to maximum light were undertaken in order to study the unique colour behaviour associated with the RCB declines. The combined recovery slope for the four stars was determined to be 3.37 ± 0.24, which is similar to the value of 3.1 ± 0.1 calculated for galactic RCB stars (Skuljan et al. 2003). These results may imply that the nature of the dust (i.e. the particle size) is similar in both our Galaxy and the MCs.

We have constructed a Main galaxy subsample of 67777 galaxies with redshifts in the range 0.08 ≤ z ≤ 0.12 from the Sloan Digital Sky Survey Data Release 3. Using cluster analysis, two isolated Main galaxy samples were extracted from this subsample. The two isolated Main galaxy samples identified at different radii have the same properties. Additionally, we find fewer early-type galaxies in isolated Main galaxy samples than in a close double galaxy sample.

The primary present-day observables upon which theories of galaxy evolution are based are a system’s morphology, dynamics, colour, and chemistry. Individually, each provides an important constraint to any given model; in concert, the four represent a fundamental (intractable) boundary condition for chemodynamical simulations. We review the current state-of-the-art semi-analytical and chemodynamical models for the Milky Way, emphasising the strengths and weaknesses of both approaches.

We describe observations with the Mopra radiotelescope designed to assess the feasibility of the H2O Maser Southern Galactic Plane Survey. We mapped two one-square-degree regions along the Galactic plane using the new 12-mm receiver and the UNSW Mopra spectrometer. We covered the entire spectrum between 19.5 and 27.5 GHz using this setup with the main aim of finding out which spectral lines can be detected with a quick mapping survey. We report on detected emission from H2O masers, NH3 inversion transitions (1,1), (2,2) and (3,3), HC3N (3–2), as well as several radio recombination lines.

The low infrared background and high atmospheric transparency are the principal advantages of Antarctic Plateau sites for astronomy. However, the poor seeing (between 1 and 3 as) negates much of the sensitivity improvements that the Antarctic atmosphere offers, compared to mid-latitude sites such as Mauna Kea or Cerro Paranal. The seeing at mid-latitude sites, though smaller in amplitude, is dominated by turbulence at altitudes of 10–20 km. Over the Antarctic Plateau, virtually no high altitude turbulence is present in the winter. The mean square error for an astrometric measurement with a dual-beam, differential astrometric interferometer in the very narrow angle regime is proportional to the integral of h 2C 2 N(h). Therefore, sites at which the turbulence occurs only at low altitudes offer large gains in astrometric precision. We show that a modest interferometer at the South Pole can achieve 10 μ as differential astrometry 300 times faster than a comparable interferometer at a good mid-latitude site, in median conditions. Science programs that would benefit from such an instrument include planet detection and orbit determination, and astrometric observation of stars microlensed by dark matter candidates.

The performance of the mysql and oracle database systems have been compared for a selection of astronomy queries using large catalogues of up to a billion objects. The queries tested are those expected from the astronomy community: general database queries, cone searches, neighbour finding and cross matching. The catalogue preparation, sql query formulation and database performance is presented. Most of the general queries perform adequately when appropriate indexes are present in the database. Each system performs well for cone search queries when the Hierarchical Triangular Mesh spatial index is used. Neighbour finding and cross matching are not well supported in a database environment when compared to software specifically developed to solve these problems.

The recent theory of propagation and generation of waves in a pulsar’s magnetosphere is discussed. In particular we consider models of pulsar radio emission due to plasma instabilities. Wave–particle interactions can lead to quasilinear diffusion increasing a particle’s pitch-angle. The recent model of γ-ray emission from synchrotron radiation as a result of quasilinear diffusion is discussed.

We present a statistical comparison between spectral line strength variations in Coma galaxies and galaxies in three rich clusters at z ~ 0.3. Using a principal component analysis, we have transformed the observable quantities, the line strengths, into new mutually orthogonal axes and found two specific results. First, more independent parameters are required to account for the line strength variations in the distant cluster data than in the Coma data, and second, line strengths which are not correlated in the distant cluster data are strongly coupled in the Coma data. These results suggest that galaxies in clusters have been homogenised such that most of the information from the conditions present at their formation has been destroyed. Hence, it may be possible that the present-day homogeneity of early-type galaxy properties, e.g. the fundamental plane relation, does not require a single formation scenario, but that a variety of formation scenarios for different galaxies could still yield the observed behaviour of nearby galaxies.

We have measured the rotational velocity of the companion star to be Ʊrot sin i= 80 ± 10 km s ˗1 (1σ) by fitting Kurucz model spectra to our observed spectrum of the black-hole candidate GRO J1655–40. From this we have calculated q = 0·31 ± 0·08, the mass of the compact object to be M1 = 7·91 ± 3·79 Mô (1σ) and for the companion starM2 = 2·76 ± 1·79 Mô(1σ), which is consistent with previous studies. We have also determined T eff = 6500 ± 50 K and [Fe/H] = −0·15 +0·15-0·10.