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The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) is a highly automated 1·7 m diameter telescope aimed at exploiting the superb submillimetre skies of the Antarctic Plateau for astronomy and aeronomy studies. It was recently installed at the Amundsen-Scott South Pole Station during the 1994/95 Austral season and is currently undergoing its first winter-over of operation. In this paper we briefly outline the capabilities of the instrument and describe some recent achievements culminating in the telescope’s first observations of the South Polar submillimetre sky.
Lynds 1642 is a small, somewhat insignificant dark cloud centred at 04h33, — 14°20 (1950). On a IIIaJ UKSTU Schmidt plate it may be seen to lie within an approximately circular patch of nebulosity which we believe to be visible by reflection. Its galactic location (l = 210°.9 b = -36°.5) places it beneath the local arm in the direction of Orion and it is likely that it is seen by reflection of the integrated light of the stars in that region of the galaxy.
One of the most difficult tasks facing theoretical astrophysics today is to find a satisfactory model for the convective transport of energy in regions where the temperature gradient is superadiabatic. A number of such models have been proposed, such as the mixing-length theory and its extensions (Vitense 1953, Böhm-Vitense 1958, Spiegel 1963, Travis and Matsushima 1973 a, b, Parson 1969), to take into account the combined effects of convection and turbulence but it is generally agreed that, to-date, no satisfactory theory has been put forward.
The time dependent multimode equations for magnetoconvection have been solved numerically for a range of parameter values and cell sizes. The solutions demonstrate the nonlinear interactions between the different scales of motion and how the induced magnetic field is concentrated into the smaller length scale. The generation of mean kinetic and magnetic helicity occurs at low Prandtl number which has significant physical interpretations in the solar situation.
Recently E. M. Burbidge and P. A. Strittmatter1 have found that the DB-like star G61-29 has broad He emission lines suggesting a rapid rotation. The purpose of this paper is to suggest a further white dwarf candidate for rapid rotation.
The Fleurs Synthesis Telescope (FST) has been used to map a number of bright, southern galactic HII regions at 1415 MHz. Descriptions of the FST can be found in Christiansen (1973) and associated papers. For the observations reported here, both the east-west and the north-south arms of the cross were used resulting in beamshapes which are nearly circular with half-power widths of 50” arc. The maps have been “cleaned” using a standard process (Högbom 1974).
There has been a great deal of progress in our understanding of planetary nebulae and their central stars during the past decade and a half. Most of this has come about through progress in observational techniques covering almost the entire electromagnetic spectrum. Theories of planetary nebula evolution have been put to better and better tests as more and more discriminating data have become available.
This review describes some of the progress made in observations and their interpretation, particularly in the context of the evolution of the nebulae and the central stars. It includes a discussion on the improved determinations of magnitudes and temperatures of the central stars, and of progress in the measurement of distances, and a reassessment of the observed mass-distribution of the central stars. The last topic has been at the centre of a lively debate for almost a decade now and has been responsible for a large number of studies of central star evolution, some this review briefly touchs upon.
This paper is based on a report given at the ASA Conference in July 1994, but takes account of subsequent developments up to the end of the year. The present state of the Two-degree Field (2dF) project for the AAT is reported. Good progress is being made on all fronts but some slippage has occurred, so that the instrument is now expected to begin astronomical observations only during the second half of 1995. An outline of other current and future instrumentation plans at the AAO is given.
Multi-frequency observations with the Culgoora radioheliograph (Wild 1967); Sheridan et al. 1973) of five solar bursts of spectral type II (Wild et al. 1954) have now been analysed. The spectra of all five bursts show split-banded harmonic structure. Each type II burst passed through only two of the heliograph’s three observing frequencies (160, 80 and 43.25 MHz). Relationships between the positions, sizes and brightness temperatures of the various sources in each burst are presented and summarized; their implications for the propagation of shock waves and radio waves in the solar corona are briefly discussed.
The LYMAN project continues the distinguished US and European tradition of the exploration of the Universe at Ultraviolet Wavelengths accessible only from space. These earlier missions, which include OAO, TD-1, ANS, Copernicus and the International Ultraviolet Explorer (IUE), each demonstrated the existence of new and hitherto unsuspected physical phenomena and processes, and have collectively enhanced our understanding of the evolution of stars, galaxies and the Universe.
The importance of both the UV-spectral region as a cornerstone of astronomical research, and of an observatory mode of operation is apparent when it is noted that observations from the IUE satellite are now cited more often than observations from any earth- or sky- based observatory. However, IUE is not eternal, and LYMAN is the next step forward, pushing the sensitivity limit down by a factor of more than 100, and opening up new fields and wavelengths of study. LYMAN is planned as a grazing incidence Wolter-Schwartzschild Type II telescope with an aperture of 80cm, feeding an array of sensitive far-UV and EUV spectrographs equipped with Photon Counting Array (PCA) detectors.
On 1922 August 20, a 20-strong scientific team, together with a naval party of 10, left Fremantle on one of the major scientific expeditions in Western Australian history. After picking up further personnel at Broome, the party proceeded to the isolated post and telegraph station of Wallal on the northern coast of Western Australia. Their task was to measure with great care the deflection of starlight by the Sun during the total solar eclipse of 1922 September 21. Specially designed photographic equipment of very high quality was used and meteorological conditions were excellent. As a result, measurements were obtained for well over a hundred stars.
A recent measurement of muon flux at energies greater than 1012 eV provides evidence for muon production by a process other than pion decay in cosmic-ray showers. Near this characteristic energy, the existing theory of weak interactions requires modification if it is not to violate a limitation (2) imposed by unitarity, which represents the conservation of probability. This work is an examination of modifications that are needed if the framework (4) of the theory is to be retained.
Infrared astronomical observations using ground-based equipment are confined to the few ‘windows’ or observation ports allowed by our absorbing atmosphere, the chief absorbing molecules being water vapour and CO2. The majority of such observations have been made using broadband filters defining the photometric J, H, K, L, M, N and O bands. Some narrow band and spectral work (essentially all photometric) has also been carried out, particularly in the 8-14 micron window. From a very few high altitude, cold, dry sites (where the integrated water vapour content of the atmosphere above the site is consistently less than 1mm), it is possible to make observations at 35 and 345 microns. In Australia, the integrated water vapour content above us is typically 15 mm, only rarely dropping below 7 mm, so that long wavelength IR measurements simply cannot be made using ground-based instruments in Australia. Water vapour is fortunately not well mixed in our atmosphere and by raising our observational platform to a high enough altitude we can in fact achieve quite high transmission for all wavelengths from 10 microns to 1 mm, where we link up with microwave observations using essentially radio techniques.
It is well known that a magnetic field has an inhibiting effect on thermal convection. It is also likely that a magnetic field might have a marked effect on the preferred cell-size and it is therefore of some importance to investigate the effect of such a field on finite amplitude convection. We restrict ourselves to fluids in which the Boussinesq approximation holds. For astrophysical application, especially in a study of the convective layer of the Sun, one should consider the compressible case but unfortunately the full compressible equations are much more difficult to handle numerically. In any case, the integration of the equations for the incompressible case will yield at least an indication of the effect of a magnetic field.