We report here a search of data recorded by the Buckland Park air shower array from the first year after the supernova and set an upper limit to the proton luminosity of SN1987A of 7.7 × 1040 ergs s−1.

Until early in 1968 radio sources were believed to be relatively constant and slowly evolving objects. Sporadic intensity variations had been found at high frequencies in some quasars but, except for the Sun and some flare stars which exhibited occasional bursts of radiation, the time scale of changing emission appeared to be very long.

Solar metre-wave noise storms commonly show continuum and short-lived narrow-band bursts (Type I) at high frequencies and fast-drift bursts (Type III) at low frequencies (Malville 1962; Hanasz 1966; Boischot et al. 1970; Moller-Pedersen 1974; see also Figs. 2-3 of this paper). The Type I and Type III emissions have the same sense of polarization (Komesaroff 1958; Suzuki 1978). Impressed by this spectral association, Malville (1962) and Boischot et al. (1970) suggested that the two types of emission might be excited by the same electron stream. However, Type I emission is associated with sunspots and strong photospheric magnetic fields (McCready et al. 1947; Payne-Scott and Little 1951; Le Squeren 1963) and for this reason Kai (1970) suggested that Type I emission arises on strong closed magnetic loops. Type III emission, by contrast, almost certainly arises on open or quasi-open (large-loop) magnetic field lines (Wild et al. 1959, 1963). Thus on these models one would expect Type I and Type III emissions to arise from different magnetic regimes and different areas of the Sun. Kai’s (1970) and Stewart and Labrum’s (1972) Culgoora radioheliograph observations, which suggested that Type I and Type III sources are always separated on the Sun, seemed to clinch the matter. Kai’s model and his statement ‘Type III sources avoid the precise location of Type I storm centres’ gained wide acceptance (e.g. Boischot et al. 1971; Elgaroy 1977; Stewart 1977).

Some self-absorbed synchrotron sources have, a small but observable degree of circular polarization rc near the absorption turnover (Roberts et al. 1975). The simplest interpretation of the circular component is in terms of the intrinsic degree of circular polarization of synchrotron radiation (Legg and Westfold 1968); this provides a relation (Roberts et al. 1975)

The theory of stellar convection zones has met three difficult problems. They are non-linearity, non-locality, and non-greyness of radiative transport. Non-linearity is inherent in turbulence. Non-locality is due to the nature of convection, that larger eddies are apt to be more unstable as indicated by the fourth-power dependence of the Rayleigh number on the vertical dimension. Inhomo-geneity and anisotropy of convection, penetration into stable layers, are the consequences. Non-grey radiative transfer through an eddy element is important in a convective atmosphere. In a preceding paper, the author has developed a theory which includes all these effects, using the representative eddy approximation. The emphasis in that paper was put rather in the non-locality and in the radiative non-greyness ; the treatment of non-linearity has been considered mainly in much earlier investigations. In the present note, we shall study how the representative eddy approximation is reconciled with the spectral theory of turbulence, and we shall determine the effective Reynolds and Péclet numbers, the coupling constants appearing in the eddy transport coefficients.

Diffusive shock acceleration produces a power law momentum distribution f(p)α p −b , with b ≥ 4 for a single shock, and b = 4 for a single strong shock. It has been shown that the distribution for acceleration at a sequence of identical shocks is flatter, approaching f(p)α p −3 below a high energy knee, for an arbitrarily large number of shocks. We show how this flatter distribution arises and discuss the range of momenta over which it extends after a finite number of shocks.

This paper is a preliminary account of the calculation of the circularly polarized synchrotron radiation received from a distribution of electricallycharged particles confined to a thin shell in the magnetic field of a dipole. Calculations of the total radiation and the degree of linear polarization have previously been carried out, and these calculations are duplicated in part.

The paper briefly describes a new publication in Japan, the bulletin ‘Teaching of Astronomy in the Asian-Pacific Region’. The author is the Chairman of the Working Committee of Teaching of Astronomy in the Asian-Pacific region of the IAU.

Surveys of the Galaxy at five frequencies in the range 2 to 20 MHz have been made using the Llanherne low frequency array (Ellis, 1972). The data has been assembled into maps covering the area 320° < £ < 30° and -25° < b < 22° and these are presented in rectangular galactic co-ordinates. Galactic radio spectra in various directions have been obtained, combining the new data with seven earlier galactic continuum surveys. The details of all the surveys used are given in Table I. A new 4.7 MHz map has been plotted from the profiles presented by Ellis and Hamilton (1966).

We discuss the properties of cyclotron radiation from accretion shocks located above the atmospheres of magnetic white dwarfs taking into account the effects of field spread and density and temparture structure. The models which are an improvement on previous point source models are shown to have characteristics that are in better overall agreement with the properties of AM Herculis type systems. Our calculations of the polarization properties of large polar cap emission regions are used to discuss the recent null measurements of circular polarization in DQ Herculis type systems.

A redistribution function R(x, x′)dx dx′ is defined as the probability that a photon with frequency between x and x + dx will be absorbed by an elemental atmosphere which then emits another photon the frequency of which lies in the range from x′ to x′ + ax′. The frequencies x and x′ are measured from the central frequency νo of the spectral line in units of the Doppler width Δ The particular functional form taken by R(x, x′) in this discussion will be given by

where α represents the broadening of the spectral line in units of the Doppler width while the function H(o, z) is defined by

the Voigt function. The function defined by means of equation (1) is one of that class of redistribution functions which combines natural and Doppler broadening. Therefore, it should be expected that any results obtained using this particular redistribution function will exhibit certain features characteristic of this type of scattering.

The relationship between the observed magnitude of a star and the air-mass takes the shape of a loop. These loops are caused by the zero-point drift of the photometer in use and by the variations of the atmospheric extinction taking place during the observation (Kviz 1979). From observations where the temperature drift of the photometer and of the photomultiplier were recorded, it is evident that the sense of the loops is correlated with the physical temperature of the photo-multiplier. Measurements have been made with the Swiss telescope and the 7-colour Geneva photometer P 7 using pulse counting with PM tube EMI9798 — described in Burnet (1976) and Burnet, Rufener (1979) — at La Silla, Chile.

The energy passing through the boundaries of a convective zone in a star, in an outward radial direction per second, must in total be equal to the luminosity of the star, provided of course that this zone does not encompass nuclear energy producing regions. If, in an endeavour to establish the nature of the convective motions in this zone, a section of the zone is modelled by considering steady cellular convection in a horizontal layer of Boussinesq fluid, it is on the basis of an average energy flux being imposed. Moreover, the sum of the conductive and convective heat fluxes is represented by the Nusselt number, which is specified and constant for the zone.

This paper summarises the opportunities available for postgraduate education in astronomy and related disciplines in China.

We have extended our recent measurements on the extraterrestrial cosmic ray electron spectrum, this spectrum now being determined over the energy range from ~15 MeV to 6 GeV. The extraterrestrial electron intensity between 15 MeV and 200 MeV can be determined unambiguously by studying the diurnal variation of these particles. We have also measured the effects of the 11-year solar modulation on the electrons, thus enabling the electron spectrum observed near the Earth to be extrapolated to the local region of the spiral arm. It is the purpose of this paper to relate these measurements to:

• (i) calculations of ‘secondary’ electrons produced by cosmic ray nuclei moving in the Galaxy; and

• (ii) the observations of non-thermal radio emission from disk components of the Galaxy.

This paper is a progress report on an examination of the short-term variability of solar proton flux in interplanetary space at times of solar flare activity. The data are from the GRCSW cosmic-ray detector on board the Pioneer 7 space probe, which, at the times to be discussed, was more than a million miles from the Earth.

Since the advent of the 80 MHz radioheliograph, precise position and polarization measurements have become available on several moving type IV bursts. Two of the more puzzling characteristics of these bursts are : (1) they exhibit strong circular polarization in parts or all of the source region ; (2) after moving outward to as much as 3 R ⊙ with relatively constant intensity, they rapidly fade away. In this paper we discuss the polarization and intensity of synchrotron radiation from mildly relativistic electrons and suggest betatron deceleration as a mechanism to explain the rapid fade-out of the moving type IV sources. The results are applied to two examples of moving type IV bursts.

We examine the nature of the redshifts of twin quasars with discrepant redshifts (θ < 100 arcsec, Δz ≥ 0.5) by considering their Hubble diagram. If such twins are physically associated one expects a large scatter in their Hubble diagram. However, we find a statistically significant linear correlation between log (cz) and Vc magnitudes of such quasars, consistent with the hypothesis that their redshifts are cosmological in nature.