Recent work has proposed that a merger event between a red-giant and a He white dwarf may be responsible for the production of R stars (Izzard, Jeffery & Lattanzio 2007). We investigate the proposed evolution and nucleosynthesis of such a model. We simulate the hypothesized late ignition of the core flash by increasing neutrino losses until ignition occurs sufficiently far from the centre that the subsequent evolution produces carbon dredge-up to the extent that the post-flash object is a carbon star. Detailed nucleosynthesis is performed within this approximation and we show that the overall properties are broadly consistent with the observations. Details will depend on the dynamics of the merger event.

In 2007 the field of nuclear astrophysics celebrated its 50th birthday.

A recent study by Wylie et al. (2006) has revealed that s-process element abundances are enhanced relative to iron in both red giant branch and asymptotic giant branch stars of 47 Tuc. A more detailed investigation into s-process element abundances throughout the colour-magnitude diagram of 47 Tuc is vital in order to determine whether the observed enhancements are intrinsic to the cluster. This paper explores this possibility through observational and theoretical means. The visibility of s- and r-process element lines in synthetic spectra of giant and dwarf stars throughout the colour magnitude diagram of 47 Tuc has been explored. It was determined that a resolving power of 10 000 was sufficient to observe s-process element abundance variations in globular cluster giant-branch stars. These synthetic results were compared with the spectra of eleven 47 Tuc giant branch stars observed during the performance verification of the Robert Stobie Spectrograph on the Southern African Large Telescope. Three s-process elements (Zr, Ba and Nd) and one r-process element (Eu) were investigated. No abundance variations were found such that [X/Fe] = 0.0 ± 0.5 dex. It was concluded that this resolving power, R ∼ 5000, was not sufficient to obtain exact abundances but upper limits on the s-process element abundances could be determined.

The kinematics of M-type (O-rich) giant semi-regular (SR) variable stars were examined. They were grouped with respect to their relative parallax errors (επ/π) in order to study the stars having relatively better parallax, and with the period limit (70 d). The spatial and velocity distributions were examined and the results were compared with the results of irregular (L) and Mira-type variables. It was found that M-type giant SR variables are distributed similarly to thin-disc stars and form a kinematically homogeneous group. When the kinematic properties of M-type giant SR variables were compared with those of L- and Mira-type variables, it was estimated that M-type giant SR variables behave as old-disc objects and their kinematic ages vary approximately between 2 and 9 Gyr.

We present a detailed reconstruction of the star-formation history of the Constellation III region in the Large Magellanic Cloud, to constrain the formation mechanism of this enigmatic feature. Star formation in Constellation III seems to have taken place during two distinct epochs: there is the 8–15 Myr epoch that had previously been recognized, but we also see strong evidence for a separate ‘burst’ of star formation 25–30 Myr ago. The ‘super-supernova' or GRB blast wave model for the formation of Constellation III is difficult to reconcile with such an extended, two-epoch star formation history, because the shock wave should have induced star formation throughout the structure simultaneously, and any unconsumed gas would quickly be dissipated, leaving nothing from which to form a subsequent burst of activity. We propose a ‘truly stochastic’ self-propagating star formation model, distinct from the canonical model in which star formation proceeds in a radially directed wave from the center of Constellation III to its perimeter. As others have noted, and we now confirm, the bulk age gradients demanded by such a model are simply not present in Constellation III. In our scenario, the prestellar gas is somehow pushed into these large-scale arc structures, without simultaneously triggering immediate and violent star formation throughout the structure. Rather, star formation proceeds in the arc according to the local physical conditions of the gas. Self-propagating star formation is certainly possible, but in a truly stochastic manner, without a directed, large scale pattern.

I discuss especially my summer with Willy Fowler at Kellogg Radiation Laboratory in 1951, where I did my ‘triple alpha’ work. I also go back even earlier to Arthur Eddington and Hans Bethe. The 1953 summer school in Ann Arbor only gets a mention.

We report radio continuum observations with the Australia Telescope Compact Array of two molecular clouds. The impetus for these observations is a search for synchrotron radiation by cosmic-ray secondary electrons/positrons in a region of enhanced density and possibly high magnetic field. We present modelling which shows that there should be an appreciable flux of synchrotron above the more diffuse, galactic synchrotron background.

The starless core G333.125–0.562 and infrared source IRAS15596–5301 were observed at 1384 and 2368 MHz. For G333.125–0.562, we find no significant levels of radio emission from this source at either frequency, nor any appreciable polarisation: we place an upper limit on the radio continuum flux from this source of 0.5 mJy beam−1 at both 1384 and 2368 MHz. Due to the higher than expected flux density limits, we also obtained archival ATCA data at 8640 MHz for this cloud and place an upper limit on the flux density of 50 μJy beam−1. Assuming the cosmic ray spectrum is similar to that near the Sun and given the cloud's molecular density and mass, we place an upper limit on the magnetic field of 500 μG.

IRAS 15596–5301, with an RMS of 50 μJy beam−1 at 1384 MHz, shows an HII region consistent with optically thin free–free emission already detected at 4800 MHz. We use the same prescription as G333 to constrain the magnetic field from this cloud to be less than 500 μG. We find that these values are not inconsistent with the view that magnetic field values scale with the average density of the molecular cloud.

Primitive meteorites and interplanetary dust particles contain small grains that originated in stellar outflows and supernova explosions. These μm- and sub-μm-sized presolar grains can be isolated and studied for their isotopic compositions in the laboratory. They are recognised as stardust by their isotopic compositions, which are completely different from those of the Solar System. They provide new information on stellar evolution, nucleosynthesis, mixing processes in asymptotic giant branch (AGB) stars and supernovae, and Galactic chemical evolution. Red giants, AGB stars, Type II supernovae and possibly novae have been identified as stellar sources of the grains. Of the eight nuclear processes proposed by Burbidge et al. (1957), signatures of all except the r-process can be found in presolar dust grains.

The Magellanic System represents one of the best places to study the formation and evolution of galaxies. Photometric surveys of various depths, areas and wavelengths have had a significant impact on our understanding of the system; however, a complete picture is still lacking. VMC (the VISTA near-infrared YJKs survey of the Magellanic System) will provide new data to derive the spatially resolved star formation history and to construct a three-dimensional map of the system. These data combined with those from other ongoing and planned surveys will give us an absolutely unique view of the system opening up the doors to truly new science!

We estimated the Galactic model parameters for a set of 36 high-latitude fields included in the currently available Data Release 5 (DR 5) of the Sloan Digital Sky Survey (SDSS), to explore their possible variation with the Galactic longitude. The thick disc scaleheight moves from ∼550 pc at 120 < l < 150° to ∼720 pc at 250 < l < 290°, while the thin disc scaleheight is as large as ∼195 pc in the anticenter direction and ∼15% lower at |l| < 30°. Finally, the axis ratio (c/a) of the halo changes from a mean value of ∼0.55 in the two first quadrants of the Galaxy to ∼0.70 at 190 < l < 300°. For the halo, the reason for the dependence of the model parameters on the Galactic longitude arises from the well known asymmetric structure of this component. However, the variation of the model parameters of the thin and thick discs with Galactic longitude originates from the gravitational effect of the Galactic long bar. Moreover, the excess of stars in quadrant I (quadrant III) over quadrant IV (quadrant II) is in agreement with this scenario.

An updated catalogue of 76 galaxies, with direct measurements of supermassive black-hole mass (Mbh) plus, when available, the central velocity dispersion (σ0) of their host bulge is provided. Fifty of these mass measurements are considered reliable, while the others remain somewhat uncertain at this time. An additional nine stellar systems, including one stellar cluster and three globular clusters, are listed as hosting potential intermediate mass black holes <106M⊙.

With this larger data set, the demographics within the Mbh–σ0 diagram are briefly explored. Many barred galaxies are shown to be offset from the Mbh–σ0 relation defined by the non-barred galaxies, in the sense that their velocity dispersions are too high. Furthermore, including 88 AGN with black-hole mass estimates from reverberation mapping studies, we speculate that barred AGN may follow this same general trend. We also show that some AGN with σ0 < 100 km s−1 tend to reside up to (∼0.6 dex) ∼1.0 dex above the (barless) Mbh–σ0 relation. Finally, it is shown that ‘core galaxies’ appear not to define an additional subdivision of the Mbh–σ0 diagram, although improved methods for measuring σ0 values may be valuable.

With the ATNF Mopra telescope we are performing a survey in the 12CO(1–0) line to map the molecular gas in the Large Magellanic Cloud. For some regions we also obtained interferometric maps of the high density gas tracers HCO+ and HCN with the Australia Telescope Compact Array. Here we discuss the properties of the elongated molecular complex that stretches about 2 kpc southward from 30 Doradus. Our data suggest that the complex, which we refer to as the ‘molecular ridge’, is not a coherent feature but consists of many smaller clumps that share the same formation history. Likely triggers of molecular-cloud formation are shocks and shearing forces that are present in the surrounding south-eastern Hi overdensity region, a region influenced by strong ram pressure and tidal forces. The molecular ridge is at the western edge of the the overdensity region where a bifurcated velocity structure transitions into a single disk velocity component. We find that the 12CO(1–0) and Hi emission peaks in the molecular ridge are typically near each other but never coincide. A likely explanation is the conversion of warmer, low-opacity Hi to colder, high-opacity Hi from which H2 subsequently forms. On smaller scales we find that very dense molecular gas, as traced by interferometric HCO+ and HCN maps, is associated with star formation along shocked filaments and with rims of expanding shell-like structures, both created by feedback from massive stars.

Starting from a sketch of the s-process concept formulated 50 years ago, the nuclear physics data for s-process calculations are briefly reviewed with emphasis on the status of neutron capture cross sections and beta decay rates. Accurate and comprehensive experimental data are mandatory as direct input for s-process calculations as well as for improving the complementary information from nuclear theory. The current challenges of the field are discussed in the light of new or optimized methods and state-of-the-art facilities, indicating the potential for accurate measurements and the possibility to study cross sections of radioactive isotopes. These opportunities will be considerably enriched by the enormous improvements provided by new facilities.

We present evidence to show that changes in the Sun's equatorial rotation rate are synchronized with changes in its orbital motion about the barycentre of the Solar System. We propose that this synchronization is indicative of a spin–orbit coupling mechanism operating between the Jovian planets and the Sun. However, we are unable to suggest a plausible underlying physical cause for the coupling. Some researchers have proposed that it is the period of the meridional flow in the convective zone of the Sun that controls both the duration and strength of the Solar cycle. We postulate that the overall period of the meridional flow is set by the level of disruption to the flow that is caused by changes in Sun's equatorial rotation speed. Based on our claim that changes in the Sun's equatorial rotation rate are synchronized with changes in the Sun's orbital motion about the barycentre, we propose that the mean period for the Sun's meridional flow is set by a Synodic resonance between the flow period (∼22.3 yr), the overall 178.7-yr repetition period for the solar orbital motion, and the 19.86-yr synodic period of Jupiter and Saturn.

We assemble a sample of galaxy clusters whose brightest members are dumbbell galaxies and compare them with a control sample in order to investigate if they are the result of recent mergers. We show that the dumbbell sample is no more likely than other clusters to exhibit subclustering. However, they are much more likely to have at least one dumbbell component possessing a significant peculiar velocity with respect to the parent cluster than a non-dumbbell brightest cluster member. We interpret this in the context of seeing the clusters at various stages of post-merger relaxation.

The Australia Telescope was used in March–April 2005 to observe the 1.384 and 2.368-GHz emissions from the RS CVn binary HR 1099 in two sessions, each of 9-h duration and 11 days apart. Two intervals of highly polarised emission, each lasting 2–3 h, were recorded. During this coherent emission we employed a recently installed facility to sample the data at 78-ms intervals to measure the fine temporal structure and, in addition, all the data were used to search for fine spectral structure. We present the following observational results: (1) ∼100% left-hand circularly polarised emission was seen at both 1.384 and 2.368 GHz during separate epochs; (2) the intervals of highly polarised emission lasted for 2–3 h on each occasion; (3) three 22-min integrations made at 78-ms time resolution showed that the modulation index of the Stokes V parameter increased monotonically as the integration time was decreased and was still increasing at our resolution limit; (4) the extremely fine temporal structure strongly indicates that the highly polarised emission is due to an electron-cyclotron maser operating in the corona of one of the binary components; (5) the first episode of what we believe is ECME (electron-cyclotron maser emission) at 1.384 GHz contained a regular frequency structure of bursts with FWHM ∼48 MHz, which drifted across the spectrum at ∼0.7 MHz min−1. Our second episode of ECME at 2.368 GHz contained wider-band frequency structure, which did not permit us to estimate an accurate bandwidth or direction of drift; (6) the two ECME events reported in this paper agree with six others reported in the literature in occurring in the binary orbital phase range 0.5–0.7; (7) in one event of 8-h duration, two independent maser sources were operating simultaneously at 1.384 and 2.368 GHz.

We discuss two kinds of maser sources that may be responsible for driving the observed events that we believe are powered by ECME. One is based on the widely reported ‘loss-cone anisotropy', the second on an auroral analogue, which is driven by an unstable ‘horseshoe' distribution of fast-electron velocities with respect to the magnetic field direction. Generally, we favour the latter, because of its higher growth rate and the possibility of the escape of radiation which has been emitted at the fundamental electron cyclotron frequency. If the auroral analogue is operating, the magnetic field in the source cavity is ∼500 G at 1.384 GHz and ∼850 G at 2.368 GHz; the source brightness temperatures are of the order TB ∼ 1015 K.

We suggest that the ECME source may be an aurora-like phenomenon due to the transfer of plasma from the K2 subgiant to the G5 dwarf in a strong stellar wind, an idea that is based on VLBA maps showing the establishment of an 8.4 GHz source near the G5 dwarf at times of enhanced radio activity in HR 1099.

We use high-resolution n-body/SPH simulations to study the hydrodynamical interaction between the Large Magellanic Cloud and the hot halo of the Milky Way. We investigate whether the ram-pressure acting on the gaseous disk of the satellite can explain the peculiarities observed in the Hi distribution and the location of the recent star formation activity.

In this talk I shall start by describing how we set about and carried out the work that led to the publication of Burbidge et al. (1957, hereafter B2FH). I then shall try and relate this work and the circumstances that surrounded it to the larger problem of the origin and formation of the universe. Here it is necessary to look back at the way that ideas developed and how, in many situations, astronomers went astray. Of course this is a personal view, though I very strongly believe that if he were still here, it is the approach that Fred Hoyle would take.

I start by describing the problems originally encountered by Gamow and his associates in trying to decide where the helium was made. This leads me to a modern discussion of the origin of 2D, 3He, 4He and 7Li, originally described by B2FH as due to the x-process. While it is generally argued, following Gamow, Alpher, and Herman, that these isotopes were synthesised in a big bang I shall show that it is equally likely that these isotopes were made in active galactic nuclei, as was the cosmic microwave background (CMB), in a cyclic universe model. The key piece of observational evidence is that the amount of energy released in the conversion of hydrogen to helium in the universe is very close to the energy carried by the CMB, namely ∼4.5 × 10−13 erg cm−3.