The earlier work on the production of deuterium in the accretion tori around Population III objects has been criticised on the basis of relative production ratios of deuterium, helium-3 and 7Li. It is shown here that the criticism on the basis of helium-3 over-production is unjustified, as no measurement of helium-3 and lithium abundances for the same stars is available. It is predicted that indeed the helium-3 abundance determination will be the best means to verify the original hypothesis.

A new distance modulus (31.23) to the Virgo cluster is derived using the distances to nearby galaxies given by Sandage and Tammann, de Vaucouleurs, ourselves and DDO observers. This when combined with the undisturbed mean Virgo cluster velocity 1182 km s-1, gives a value for the global Hubble constant as 67 ±4 km s-1Mpc-1.

At present there are two general theories of the origin of cosmic rays. One is that most, if not all, galactic cosmic rays originate within the Galaxy, probably during supernova explosions. The other is that cosmic rays pervade the universe, originating mainly in the powerful radio galaxies and possibly in quasars, where vast stores of energy are available. The former theory has been discussed in detail by Ginzburg and Syrovatskii, while proponents of the latter theory include Burbidge and Hoyle, and Burbidge.

The Windsor amateur astronomer, John Tebbutt, had a ceased observing in 1907. However, in 1909, at the age of 75, he came out of retirement to observe Halley’s comet and his astrometric positions were published in the Monthly Notices of the Royal Astronomical Society. These data were used, together with most published observations from the 1835 and 1910 apparitions, for the computation of Halley’s orbit for ESA’s Halley intercept spacecraft, Giotto. A detailed analysis of the observations have shown minor imperfections that, when corrected, gave rms errors of 3''.5 arc in right ascension and 2''.8 in declination. His systematic errors are negligible at the 0''.2 level.

We summarise recent developments in modelling SN 1987A including the progenitor’s evolution, explosive nucleosynthesis, optical, X- and γ-ray light curves, and dust formation. The distribution of heavy elements in the ejecta is inferred from the light curves. The pre-peak optical light curve as well as early emergence of X- and γ-ray indicate the mixing of 56Ni into the hydrogen-rich envelope. The plateau-like peak of the optical light curve is well reproduced if hydrogen is mixed into the deep core. The flat X-ray light curve observed by Ginga would be due to the clumpy structure of the core. The progenitor’s blue-red-blue evolution and nitrogen abundance suggest that the progenitor’s hydrogen-rich envelope had mass M env = 7 − 11 M⊙ and was almost completely mixed.

A general method is described for estimating the position, integrated flux density and the second moments of the flux density distribution for sources in a two dimensional map. The method requires accurate knowledge of the beam shape of the telescope. Uncertainty estimates and significance levels of the source parameters are easily obtained.

Over the past three years, using the Parkes Telescope, accurate positions of over 700 extragalactic radio sources have been obtained for the purpose of optical identification of the sources.

As shown recently by Y. Osaki super-massive stars with mass M < 3.5 × 105M⊙ can, in the absence of rotation, reach the hydrogen-burning main sequence before the onset of general relativistic instability. Such objects are then pulsationally unstable. A considerable simplification is introduced if one considers only very massive stars, for which the relative amplitude of the fundamental mode of oscillation is practically constant. This sets a lower limit of 104 M⊙ to the mass that can be considered. The upper limit is also reduced to 2 × 105M⊙ if one neglects the relativistic correction. One necessary step in the study of non-linear oscillations of massive stars is to derive a differential equation for the adiabatic pulsations. The relativistic correction could be taken into account in the following way.

The radio installations at Culgoora Observatory evolved from the work carried out at Dapto field station between 1952 and 1965—which in turn was based on earlier observations. The basic instrument at Dapto was a radiospectrograph which produced two solar spectra per second over a frequency range originally of 40-210 MHz and finally of 5-2000 MHz. Until 1957 the Dapto radio spectrograph was the only one operating in the world and it fell upon this instrument to reveal many of the spectral phenomena which are now well known. The spectrograph observations referred to the total flux from the Sun observations with high directivity began at Dapto in 1958 with the introduction of a swept-frequency interferometer which measured the one-dimensional (east-west) positions of bursts and their approximate angular size over a continuous range of frequencies between 40 and 70 MHz. The results obtained from this combination of spectrograph and interferometer indicated that great advances would be made in our knowledge and understanding of the phenomena if two-dimensional metre-wavelength pictures of the Sun could somehow be recorded at short time intervals of about Is—again in combination with spectrographic observations. This requirement led to the start of the radioheliograph project. One requirement for this instrument was a site with linear dimensions of the order of 3x3 km. This was far too large for the Dapto site and a new site was selected at Culgoora in the north-west plains of New South Wales. The virtues of this site are its size, flatness, freedom from flooding, low radio noise level and accessibility from Sydney by air transport. Its sunshine and optical-seeing properties also made it a highly desirable site for optical observations, and developments assumed a new significance when Dr. Giovanelli and his optical colleagues decided to join us at the same observatory.

Coronae Austrinae is one of the few star formation areas lying well away from the galactic plane (l = 360°, b = −17°) and is visible predominantly from the Southern Hemisphere.

We present here the best of a series of models of the Magellanic stream. The dominant force in these models is gas drag. Gaseous cloudlets are torn from the bridge between the Large and Small Magellanic Clouds as the Magellanic system passes through a hot gaseous halo about our galaxy. The cloudlets are then stretched apart from each other by tidal and drag forces to form the Magellanic stream. Our best model closely reproduces the position of the stream on the sky and the run of radial velocities along the Magellanic stream. The agreement is almost as good as the best purely tidal model. In our best model the Magellanic system is only loosely bound to our galaxy and is on the first encounter with it. This overcomes some of the problems with purely tidal models. Our series of models indicate that there is a wide range of parameters that will produce a reasonable stream under the forces of gas drag and gravity.

The innermost Galilean satellite of Jupiter, Io, has been observed to strongly modulate the probability and intensity of Jupiter’s decametric emissions. The effect is most pronounced at frequencies greater than 30 MHz. Radiation occurs from two configurations of Jupiter and Io, the first when Io is 90° from superior geocentric conjunction (s.g.c.) and Jupiter’s longitude is near 120°, and the second when Io is 240° from s.g.c. and Jupiter’s longitude is near 230°.

It has been suggested, for example by Wilson and Spiegel, that the results from the study of convection in incompressible fluids may provide a basis for the study of the solar convection zone. In fact Wilson’s models contain temperature fluctuation maxima, a feature exhibited by the results obtained from the convection problem for large values of the Rayleigh number.

The paraboloid primary mirror of a classical reflecting telescope gives an image that is perfectly corrected for spherical aberration and free from chromatic aberration. However, the image suffers from coma, astigmatism and field curvature. These aberrations severely limit the usable field. For example, the primary mirror of the 200 inch telescope gives an acceptable image of a field with a diameter of only ~2’ arc.

Radio measurements of the outer planets at wavelengths longer than ~ 10 cm are difficult: the emission is weak (generally following an optically thick thermal spectrum — i.e. S ∝ λ-2) and the confusion due to background sources may be large.

A new mechanism of thermonuclear reaction is briefly introduced. It shows that a certain amount of thermonuclear reaction can take place in dense, low temperature (T < 1 × 105 K) plasmas. As most regions in the Sun are at moderate and low temperature, a sufficient amount of fusion energy is generated there. Therefore, the current standard solar models, in which the solar central temperature must be slightly lower than 15 × 106 K, must be modified, and this would make the flux of high-energy neutrinos conform with the observational results.

The exact formula for the intensity of synchrotron radiation emitted by a single charged particle in vacuo was given by Schott, for the case of circular orbits, and Takakura for the case of helical orbits. In the general case the radiated power is expressed in terms of four variables which appear in (among other places) the arguments or orders of a Bessel function and its first derivative; hence the general formula gives little insight into the interpretation of synchrotron radiation and allows evaluation only in particular cases. There is a particular need for approximate formulae that yield the spectrum of the radiation in explicit form. Such approximate formulae were found by Vladimirskii and Schwinger for the case of highly relativistic electrons. In the present paper we outline the derivation of approximate formulae applicable to mildly relativistic electrons, especially those with velocity βc such that 0 ≪ β ≲ O.9. These approximations are also relevant to the case of highly relativistic electrons in a plasma with refractive index appreciably less than unity.