I present measurements of the projected rotational velocities of a sample of 100 early B-type main-sequence stars in the Large Magellanic Cloud (LMC). This is the first extragalactic study of the distribution of stellar rotational velocities. The sample is drawn from two sources: from the vicinity of the main-sequence turnoff of young clusters (ages 1–3 × 107 yr) and from the general field. I find that the cluster population exhibits significantly more rapid rotation than that seen in the field. I have drawn analogous Galactic cluster and field samples from the literature. Comparison of these samples reveals the same effect. I propose that the observed difference between cluster and field populations can be explained by a scenario of evolutionary enhancement of the surface angular momentum over the main-sequence lifetime. A comparison is made between the cluster and field populations of the LMC and the Galaxy in order to explore the effects of metallicity. This shows that the stars of the LMC are more rapid rotators than their Galactic counterparts.

We study the effect of different star formation regimes on the dynamical and chemical evolution of IZw18, the most metal-poor dwarf galaxy locally known. To do that we adopt a two-dimensional hydrocode coupled with detailed chemical yields originating from Type II and Type Ia supernovae and from intermediate-mass stars. Particular emphasis is devoted to the problem of mixing of metals. We conclude that, under particular conditions, cooling of metals occurs with a timescale of the order of 10 Myr, thus confirming the hypothesis of instantaneous mixing adopted in chemical evolution models. We try to draw conclusions about the star formation history and the age of the last burst in IZw18.

Large-lecture introductory astronomy courses for undergraduate, non-science majors present numerous problems for faculty. As part of a systematic effort to improve the course learning environment, a series of small-group, collaborative learning activities were implemented in an otherwise conventional lecture astronomy survey course. These activities were used once each week during the regularly scheduled lecture period. After eight weeks, ten focus group interviews were conducted to qualitatively assess the impact and dynamics of these small group learning activities. Overall, the data strongly suggest that students enjoy participating in the in-class learning activities in learning teams of three to four students. These students firmly believe that they are learning more than they would from lectures alone. Inductive analysis of the transcripts revealed five major themes prevalent among the students' perspectives: (1) self-formed, cooperative group composition and formation should be more regulated by the instructor; (2) team members' assigned rolls should be less formally structured by the instructors; (3) cooperative groups helped in learning the course content; (4) time constraints on lectures and activities need to be more carefully aligned; and (5) gender issues can exist within the groups. These themes serve as a guide for instructors who are developing instructional interventions for large lecture courses.

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 have obtained HST/STIS long slit spectroscopy of the aligned emission line nebulae in three compact steep spectrum (CSS) radio sources — 3C 67, 3C 277.1, and 3C 303.1. We find systematic offsets (˜300–500 kms) of the emission line velocities on one or both sides of the radio sources. We also see evidence for broad lines (FWHM ˜500 kms) and complex emission line profiles. In 3C 303.1 the data are consistent with multiple components and possibly split lines. The amplitude of the velocity variations is not so large as to exclude gravitationally-induced motions. However, the complex kinematics, the lack of a signature of Keplerian rotation, and the association of the velocity variations with the radio lobes are consistent with the observed ˜300–500 kms velocities being driven by the expansion of the radio source. Acceleration of the clouds by the bow shock is plausible given the estimated densities in the clouds and the velocities observed in the much smaller compact symmetric objects and with expansion velocities estimated from spectral ageing. This conclusion is unchanged if we consider the scenario in which the cloud acceleration is dominated by the post bow shock flow.

We present a catalogue of the 322 damped Lyman alpha absorbers taken from the literature. All damped Lyman alpha absorbers are included, with no selection on redshift or quasar magnitude. Of these, 123 are candidates and await confirmation using high resolution spectroscopy. For all 322 objects we catalogue the radio properties of the background quasars, where known. Around 60 quasars have radio flux densities above 0.1 Jy and approximately half of these have optical magnitudes brighter than V = 18. This compilation should prove useful in several areas of extragalactic/cosmological research.

Detection of cosmic-ray hits is important because of their disturbing effects on image processing. An algorithm based on gray-scale morphology to detect cosmic-rays in single spectroscopic CCD images is presented in this paper. Based on the morphological differences between cosmic-ray hits and spectra, the operations of erosion and dilation are used to deal with images successively, with appropriate structuring elements. Points of cosmic-ray hits can be detected by analyzing the variation between data pre- and post-operation. Examples of the algorithm are given at the end of this paper, with several groups of both simulated LAMOST images and observed SDSS images to show its performance.

I review the capabilities of Hα observations to constrain some aspects of the current models of the interstellar medium. In particular, it is shown that turbulence is a necessary ingredient of any viable model, since most of the energy produced by supernova explosions and ionising radiation is stored in kinetic form in the ISM. Various forms of turbulent energy dissipation, including cloud collisions, are analysed. Two additional aspects, concerning the existence of galactic fountains and their relation with high-velocity Clouds, and the extended ionised layer of spiral galaxies are discussed; some crucial experiments are suggested.

We present images of Mars obtained in the 2.0 μm CO2 band with the United Kingdom Infrared Telescope (UKIRT). The images reveal topographic features of the Martian surface that are usually invisible in direct albedo images at visible or IR wavelengths, but agree remarkably well with the topography of the planet as mapped by the MOLA instrument on Mars Global Surveyor. The CO2 band depth is a measure of the absorbing column of CO2 and hence determined primarily by the surface atmospheric pressure. The surface pressure variations are detected with a sensitivity of 4–5 Pa. We compare our data with radiative transfer models and find that the measured CO2 variation with pressure is consistent with the models. We discuss the possibility that similar observations might be used to observe atmospheric pressure changes due to Martian weather systems.

Presolar grains in meteorites formed in a sample of Asymptotic Giant Branch (AGB) stars that ended their lives within ≈1 Gyr of the origin of the Solar System 4.6 Gyr ago. The O-isotopic compositions of presolar O-rich stardust reflect the masses and metallicities of their parent stars. We present simple Monte Carlo simulations of the parent AGB stars of presolar grains. Comparison of model predictions with the grain data allow some broad conclusions to be drawn: (1) Presolar O-rich grains formed in AGB stars of mass ∼1.15–2.2 M⊙. The upper-mass cutoff reflects dredge-up of C in more massive AGB stars, leading to C-rich dust rather than O-rich, but the lack of grains from intermediate-mass AGB stars (>4 M⊙) is a major puzzle; (2) The grain O-isotopic data are reproduced well if the Galaxy in presolar times was assumed to have a moderate age-metallicity relationship, but with significant metallicity scatter for stars born at the same time; (3) The Sun appears to have a moderately low metallicity for its age and/or unusual 17O/16O and 18O/16O ratios for its metallicity; and (4) The Solar 17O/18O ratio, while unusual relative to present-day molecular clouds and protostars, was not atypical for the presolar disk and does not require self-pollution of the protosolar molecular cloud by supernova ejecta.

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.

We report on a preliminary analysis of a 5600 sec per point survey of 32 square degrees in Centaurus, carried out with the Parkes 13-beam system. The signal-to-noise ratio is found to improve as for the whole integration. We have detected 102 HI sources between +250 and +12,700 km s−1 either by eye or by using the new galaxy-finding algorithm PICASSO. Over half of these are new HI detections. Around a dozen of these are not associated with catalogued galaxies and, in two of these cases, we have not identified an optical counterpart on the Digitized Sky Survey. Arguments are put forward to explain why deep integrations are needed to find low surface brightness objects.

We present a statistical analysis of the interactions between satellite galaxies in cosmological dark matter halos taken from fully self-consistent high-resolution simulations of galaxy clusters. We show that the number distribution of satellite encounters has a tail that extends to as many as three to four encounters per orbit. On average 30% of the substructure population had at least one encounter (per orbit) with another satellite galaxy. However, this result depends on the age of the dark matter host halo with a clear trend for more interactions in younger systems. We also report a correlation between the number of encounters and the distance of the satellites to the centre of the cluster — satellite galaxies closer to the centre experience more interactions. However, this can be simply explained by the radial distribution of the substructure population and merely reflects the fact that the density of satellites is higher in those regions.

In order to find substructure galaxies we applied (and present) a new technique based upon the N-body code MLAPM. This new halo finder MHF (MLAPM’s halo finder) acts with exactly the same accuracy as the N-body code itself and is therefore free of any bias and spurious mismatch between simulation data and halo finding precision related to numerical effects.

Since the recent upgrades to the Australia Telescope National Facility (ATNF) Mopra telescope back-end and receiver system, it has risen from an under-subscribed facility to a sought-after instrument with heavy international competition to gain time. Furthermore, the introduction of the on-the-fly mapping capability in 2004 has made this technique one of Mopra's most popular observing modes. In addition, the recent upgrade of the NANTEN millimetre-wavelength telescope to the sub-millimetre NANTEN2 instrument, has provided a complementary, higher-frequency facility to Mopra. A two-day workshop was held at Swinburne University in June 2008 to disseminate the current state of ongoing large-scale mapping projects and associated spin-offs that the telescopes' upgrades have facilitated, and to decide upon future research directions. Here, we provide a summary of the result-oriented talks as a record of the state of Australian-access single-dish millimetre science in 2008.

The PULSE@Parkes project has been designed to monitor the rotation of radio pulsars over time spans of days to years. The observations are obtained using the Parkes 64-m and 12-m radio telescopes by Australian and international high school students. These students learn the basis of radio astronomy and undertake small projects with their observations. The data are fully calibrated and obtained with the state-of-the-art pulsar hardware available at Parkes. The final data sets are archived and are currently being used to carry out studies of 1) pulsar glitches, 2) timing noise, 3) pulse profile stability over long time scales and 4) the extreme nulling phenomenon. The data are also included in other projects such as gamma-ray observatory support and for the Parkes Pulsar Timing Array project. In this paper we describe the current status of the project and present the first scientific results from the Parkes 12-m radio telescope. We emphasise that this project offers a straightforward means to enthuse high school students and the general public about radio astronomy while obtaining scientifically valuable data sets.

The five-minute oscillations in the Sun have provided a wealth of information about the solar interior. After many attempts, positive detections of similar oscillations in solar-type stars have now been made. This review discusses the properties of solar-like oscillations, the methods used to observe them, and the results on individual stars. We conclude that the study of solar-like oscillations from the ground and space has an exciting future.

The E. & F. White Conference held in Sydney in December 1999 brought together expertise on a range of interference mitigation techniques from CSIRO, Australian and international industry and universities. Key goals were to enhance the understanding of techniques and their inter-relationship, to increase awareness of advanced technologies such as software radios and photonics, and to foster a cooperative approach to the development of interference mitigation techniques. The foremost application in mind was the square kilometre array (SKA) and the need to find ways to develop a hierarchical scheme for removing unwanted signals from astronomical data. This paper gives an overview of the topics discussed at the conference and summarises some of the key ideas and results that were presented.

The Algol type eclipsing binary KZ Pav has been observed over one complete orbit (0.95 days) with theAustraliaTelescope CompactArray. Contemporaneous optical photometric data from the University of Southern Queensland’s Observatory at Mount Kent were also collected and have been included in this multi-wavelength study.

Preliminary indications are that the low levels of emission observed share similarities to those of some RS CVn binaries. The optical data show phase-linked effects which can be related to the mass transfer process of Algols. The possibility that the radio emission may be related to this process is considered.

We present a study of X-ray column density variability in Seyfert 2 galaxies. We show that variations in NH are observed in almost all the objects with multiple hard X-ray observations. Variation timescales (as short as a few months in several cases) are not in agreement with the standard scenario of a parsec-scale toroidal absorber. We propose that the X-ray absorber in Seyfert galaxies is located much nearer to the centre than previously assumed, on the broad line region scale. An extension of the model by M. Elvis (2000) can explain the observed variability. We also show preliminary results of NH variability search inside single X-ray observations, which suggest that variations can occur on timescales of a few 104 s.

The abundance of the neutron-rich magnesium isotopes observed in metal-poor stars is explained quantitatively with a chemical evolution model of the local Galaxy that considers — for the first time — the metallicity-dependent contribution from intermediate mass stars. Previous models that simulate the variation of Mg isotopic ratios with metallicity in the solar neighbourhood have attributed the production of 25Mg and 26Mg exclusively to hydrostatic burning in massive stars. These models match the data well for [Fe/H] > –1.0 but severely underestimate 25,26Mg/24Mg at lower metallicities. Earlier studies have noted that this discrepancy may indicate a significant role played by intermediate mass stars. Only recently have detailed calculations of intermediate mass stellar yields of 25Mg and 26Mg become available with which to test this hypothesis. In an extension of previous work, we present a model that successfully matches the Mg isotopic abundances in nearby Galactic disk stars through the incorporation of nucleosynthesis predictions of Mg isotopic production in asymptotic giant branch stars.