The Culgoora-3 list of radio sources (Slee 1977) contains measurements at 160 MHz of about 2000 sources which had earlier been examined at 80 MHz (Slee and Higgins 1973, 1975). The observations were made with the Culgoora radioheliograph, a 3-km-diameter ring of 96 reflectors, which achieves angular resolutions (full half-power width) of 3′.7 and 1′.9 arc at 80 and 160 MHz respectively; it has an effective collecting area of ~6000 m2.

Photoelectric B and V light curves and high dispersion spectroscopic observations were obtained in 1985 February for the rapidly rotating spotted star HD 36705. The visual light range was about 0.09 magnitude, with a well correlated B-V change of approximately 0.04 magnitude, the star being redder when faintest. There is evidence for a broadband flare of ~0.05 magnitude in V and 0.07 magnitude in B. This occurred near maximum light.

Spectroscopic observations show a variation in the equivalent width of the Ca K emission by a factor of about two in antiphase with the photometric variations, maximum emission corresponding to minimum brightness. This is probably due to bright plages and enhanced chromospheric heating associated with the photospheric starspots.

High dispersion, high signal-to-noise spectroscopic observations confirm the presence of lithium λ 6708 as reported by Rucinski (1982, 1985).

Several interpretations of the nature of HD 36705 are discussed; however at present none is completely satisfactory and further observations are required. As the star is probably at less than 100 pc, a parallax determination may be possible, and could help answer many of the questions concerning HD 36705.

Over the past few years, site-testing at the South Pole has revealed conditions that are uniquely favourable for infrared astronomy. In particular, the exceptionally low sky brightness throughout the near and mid-infrared leads to the possibility of a modest-sized telescope achieving comparable sensitivity to that of existing 8–10 metre class telescopes. An 8 metre Antarctic telescope, if constructed, would yield performance that would be unrivalled until the advent of the NGST. In this paper we review the scientific potential of infrared telescopes in Antarctica, and discuss their complementarity with existing 8–10 metre class telescopes and future proposed space telescopes. In particular, we discuss the role that a 2 metre class infrared telescope plays in future plans for the development of an observatory on the Antarctic plateau.

We present here a preliminary report and commentary of recently processed observations of Hα emission towards the Magellanic Bridge. These data have been analysed in an attempt to quantify the extent to which the stellar population is capable of reshaping the local ISM. We find that the Hα emission regions are small, weak and sparsely distributed, consistent with a relatively quiescent and inactive ISM where radiative and collisional ionisation is inefficient and sporadic. This suggests that energetic processes at the small scale (i.e. ∼tens of pc) do not dominate the energy balance within the ISM of the Bridge, which therefore hosts a pristine turbulent structure, otherwise inaccessible within our own Galaxy. We find Hα emission that is well correlated with detected 12CO(1–0) line emission (a proxy for molecular hydrogen), as well as other easily identified ring-like Hı features.

Planetary nebulae (PNe) can be roughly categorized into several broad morphological classes. The high quality images of PNe acquired in recent years, however, have revealed a wealth of fine structures that preclude simplistic models for their formation. Here we present narrow-band, sub-arcsecond images of a sample of relatively large PNe that illustrate the complexity and variety of small-scale structures. This is especially true for bipolar PNe, for which the images reveal multi-polar ejections and, in some cases, suggest turbulent gas motions. Our images also reveal the presence or signs of jet-like outflows in several objects in which this kind of component has not been previously reported.

Modelling of extreme scattering events suggests that the Galaxy's dark matter is an undetected population of cold, AU-sized, planetary-mass gas clouds. None of the direct observational constraints on this picture—thermal/non-thermal emission, extinction and lensing—are problematic. The theoretical situation is less comfortable, but still satisfactory. Galactic clouds can survive in their current condition for billions of years, but we do not have a firm description for either their origin or their evolution to the present epoch. We hypothesise that the proto-clouds formed during the quark–hadron phase transition, thereby introducing the inhomogeneity necessary for compatibility with light element nucleosynthesis in a purely baryonic universe. We outline the prospects for directly detecting the inferred cloud population. The most promising signatures are cosmic-ray-induced Hα emission from clouds in the solar neighbourhood, optical and X-ray flashes arising from cloud–cloud collisions, ultraviolet extinction, and three varieties of lensing phenomena.

Circumstellar imaging across the electromagnetic spectrum allows us to derive fundamental diagnostics for the physics of mass loss in the Asymptotic Giant Branch (AGB) phase. I review the current status of the field, with particular emphasis on the techniques that provide the strongest constraints for mass-loss modeling efforts.

In the search for tidal structure in Galactic satellite systems, we have conducted a photometric survey over a 10 deg2 area centred on the Fornax dSph galaxy. The survey was made in two colours, and the resulting colour–magnitude data were used as a mask to select candidate Fornax RGB stars, thereby increasing the contrast of Fornax stars to background sources in the outer regions. Previously, we reported the presence of a shell (age 2 Gyr) located towards the centre of Fornax. In this contribution we reveal a second shell, significantly larger than the first, located 1.3° north-west from the centre of Fornax, outside the nominal tidal radius. Moreover, the distribution of Fornax RGB stars reveals two lobes extending to the spatial limit of our survey, and aligned with the minor axis and with the two shells. These results support the hypothesis of a merger between Fornax and a gas-rich companion approximately 2 Gyr ago.

We produce the first low to mid-frequency radio simulation that incorporates both traditional extragalactic radio sources as well as synchrotron cosmic web emission. The FIlaments & GAlactic RadiO (FIGARO) simulation includes 10 unique 4° × 4° fields, incorporating active galactic nucleii (AGNs), star-forming galaxies (SFGs), and synchrotron cosmic web emission out to a redshift of z = 0.8 and over the frequency range 100–1 400 MHz. To do this, the simulation brings together a recent 1003 Mpc3 magnetohydrodynamic simulation (Vazza et al. 2019, A&A, 627, A5), calibrated to match observed radio relic population statistics, alongside updated ‘T-RECS’ code for simulating extragalactic radio sources (Bonaldi et al. 2019, MNRAS, 482, 2). Uniquely, the AGNs and SFGs are populated and positioned in accordance with the underlying matter density of the cosmological simulation. In this way, the simulation provides an accurate understanding of the apparent morphology, angular scales, and brightness of the cosmic web as well as—crucially—the clustering properties of the cosmic web with respect to the embedded extragalactic radio population. We find that the synchrotron cosmic web does not closely trace the underlying mass distribution of the cosmic web, but is instead dominated by shocked shells of emission surrounding dark matter halos and resembles a large, undetected population of radio relics. We also show that, with accurate kernels, the cosmic web radio emission is clearly detectable by cross-correlation techniques and this signal is separable from the embedded extragalactic radio population. We offer the simulation as a public resource towards the development of techniques for detecting and measuring the synchrotron cosmic web.

We study the phase mixing and dissipation of a packet of standing shear Alfvén waves localized in a region with non-uniform Alfvén background velocity. We investigate the validity of the exponential damping law in time, exp (–At3), presented by Heyvaerts & Priest (1983) for different ranges of Lundquist, S, and Reynolds, R, numbers. Our numerical results shows that it is valid for (R,S) ≥ 107.

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.

This paper presents results from speckle observations of binary stars carried out between 1987 and 1990 using a 212-cm telescope at the San Pedro Martir Observatory, Mexico.

We investigate the regular or chaotic nature of orbits of stars moving in the meridional plane (R, z) of an axially symmetric galactic model with a dense, massive spherical nucleus and a dark matter halo component. In particular, we study the influence of the fractional portion of the dark matter, by computing in each case the percentage of chaotic orbits, as well as the percentages of orbits of the main regular resonant families. In an attempt to distinguish between regular and chaotic motion, we use the fast Lyapunov indicator method to extensive samples of orbits obtained by integrating numerically the equations of motion as well as the variational equations. Furthermore, a technique which is based mainly on the field of spectral dynamics that utilises the Fourier transform of the time series of each coordinate is used for identifying the various families of regular orbits and also to recognise the secondary resonances that bifurcate from them. Two cases are studied in our work: (i) the case where we have a disk galaxy model and (ii) the case where our model represents an elliptical galaxy. A comparison with early related work is also made.

Accurate automatic identification of astronomical objects in an imperfect world of non-linear wide-angle optics, imperfect optics, inaccurately pointed telescopes, and defect-ridden cameras is not always a trivial first step. In the past few years, this problem has been exacerbated by the rise of digital imaging, providing vast digital streams of astronomical images and data. In the modern age of increasing bandwidth, human identifications are many times impracticably slow. In order to perform an automatic computer-based analysis of astronomical frames, a quick and accurate identification of astronomical objects is required. Such identification must follow a rigorous transformation from topocentric celestial coordinates into image coordinates on a CCD frame. This paper presents a fuzzy logic based algorithm that estimates needed coordinate transformations in a practical setting. Using a training set of reference stars, the algorithm statically builds a fuzzy logic model. At runtime, the algorithm uses this model to associate stellar objects visible in the frames to known cataloged objects, and generates files that contain photometry information of objects visible in the frame. Use of this algorithm facilitates real-time monitoring of stars and bright transients, allowing identifications and alerts to be issued more reliably. The algorithm is being implemented by the Night Sky Live all-sky monitoring global network and has shown itself significantly more reliable than the previously used non-fuzzy logic algorithm.

Taking into account results obtained from light-curve analysis and out-of-eclipse analyses, we discuss the nature of GSC 02038-00293 and also its magnetic activity behaviour.We obtained light curves of the system during observing seasons 2007, 2008 and 2011. We obtained its secondary minimum clearly in I-band observations in 2008 for the first time. Analysing this light curve, we found the physical parameters of the components. The light-curve analysis indicates that the possible mass ratio of the system is 0.35. We obtained the remaining V-band light curves, extracting the eclipses. We modelled these remaining curves using the SPOTMODEL program and found possible spot configurations of the magnetically active component for each observing season. The models demonstrated that there are two active longitudes for the active component. The models reveal that both active longitudes migrate in the direction of decreasing longitude. We also examined the light curves in out-of-eclipse phases with respect to minimum and maximum brightness, amplitude, etc. The amplitude of the curves during out-of-eclipse phases varies in a sinusoidal way with a period of ∼8.9 yr; the mean brightness of the system is dramatically decreasing. The phases of the deeper minimum during out-of-eclipse periods exhibit a migration toward decreasing phase.

We describe the dynamical behavior of isolated old ( ⩾ 1Gyr) objects-like Neutron Stars (NSs). These objects are evolved under smooth, time-independent, gravitational potentials, axisymmetric and with a triaxial dark halo. We analysed the geometry of the dynamics and applied the Poincaré section for comparing the influence of different birth velocities. The inspection of the maximal asymptotic Lyapunov (λ) exponent shows that dynamical behaviors of the selected orbits are nearly the same as the regular orbits with 2-DOF, both in axisymmetric and triaxial when (ϕ, qz)= (0,0). Conversely, a few chaotic trajectories are found with a rotated triaxial halo when (ϕ, qz)= (90, 1.5). The tube orbits preserve direction of their circulation around either the long or short axis as appeared in the triaxial potential, even when every initial condition leads to different orientations. The Poincaré section shows that there are 2-D invariant tori and invariant curves (islands) around stable periodic orbits that bound to the surface of 3-D tori. The regularity of several prototypical orbits offer the means to identify the phase-space regions with localized motions and to determine their environment in different models, because they can occupy significant parts of phase-space depending on the potential. This is of particular importance in Galactic Dynamics.

Radial-velocity observations accumulated during the past 16 years are used to derive a preliminary orbit for the CEMP star CS 22881–036. The velocity amplitude is very small. No velocity variation is found for three additional CEMP stars observed over roughly the same time interval. Searches for companions of two CEMP double-lined spectroscopic binaries and of the RR Lyrae star TY Gru are reviewed. A disparity between the period distribution of disk carbon-star binaries and that of their parent population of normal binaries can be attributed qualitatively to a decline in accreted mass with increasing binary separation. Finally, possible reasons for failure to find expected companions of CEMP stars are discussed.

The extended radio source 0319-453 (MSH 03-43) was observed with the Molonglo Observatory Synthesis Telescope as part of a program to study a large sample of southern extragalactic radio sources. The low level structure showed a ridge pointing towards the nearby source 0317-456, which also showed low level structure. It is suggested that the two sources are the asymmetric lobes of a radio galaxy identified with the magnitude 15 peculiar dust-land galaxy AM 0319-452. The galaxy redshift of z = 0.0633 and the radio size of 25.6 arcmin give a projected size of 1.27 Mpc (H = 100 kms−1 Mpc−1). Thus it is one of the largest radio galaxies.

A cloud with a l.s.r. velocity of ∼ 160 km s-1 and a half-width of ∼ 25 km s-1 was mapped in the (1,1), (2,2) and (4,4) lines of para NH3 and the (3,3) and (6,6) lines of ortho NH3 using the 40″ arc beam of the 100-m Effelsberg telescope. The cloud was extended some 5′ in latitude and contained a central concentration ∼ 1′.5 in size at ℓ = 1°.59; b=0°.01. Line temperatures of the four higher transitions define a rotational temperature of ∼ 120 K, while the (1,1) and (2,2) alone yield the lower value of ∼ 40 K. The high temperatures, well above that of the dust, are too high to be caused by collisions with H2 molecules in the ground state, but might result from collisions with H2 in excited states. On a (ℓ, v) plot the cloud does not coincide with any generally accepted galactic centre feature but it is possibly located near the periphery of the ‘rotating nuclear disk’, where conditions would be favourable for the production of shocks, excited H2 and possibly high NH3 temperatures.

Due to the foreground extinction of the Milky Way, galaxies become increasingly faint as they approach the Galactic Equator creating a ‘zone of avoidance’ (ZOA) in the distribution of optically visible galaxies of about 25%. A ‘whole-sky’ map of galaxies is essential, however, for understanding the dynamics in our local Universe, in particular the peculiar velocity of the Local Group with respect to the Cosmic Microwave Background and velocity flow fields such as in the Great Attractor (GA) region. The current status of deep optical galaxy searches behind the Milky Way and their completeness as a function of foreground extinction will be reviewed. It has been shown that these surveys—which in the mean time cover the whole ZOA (Figure 2)—result in a considerable reduction of the ZOA from extinction levels of AB =1m.0 (Figure 1) to AB =3m.0 (Figure 3). In the remaining, optically opaque ZOA, systematic HI surveys are powerful in uncovering galaxies, as is demonstrated for the GA region with data from the full sensitivity Parkes Multibeam HI survey (300°≤l≤332°, ∣b∣≤5°.5, Figure 4).