We report continuum observations of the NGC 7538–IRS 1, 2 and 3 regions made with the NRO 45-metre dish between 43 and 90 GHz, and present a brief interpretation.

High-speed photometry of two cataclysmic variables is presented. The observations were made using a two-channel photometric system and the Mt John 0.6 or 1-m telescopes at Lake Tekapo in New Zealand. Both objects have only recently been identified as cataclysmic variables. One of the objects is a high inclination system featuring a deep eclipse in the light curve and a 5.5 hour period, while the other object, despite being relatively faint, clearly exhibits a 2.5 hour period and out of eclipse variability. Simultaneous monitoring of a nearby comparison star for this latter object was particularly beneficial, even during good photometric conditions.

We have secured spectra at high signal/noise ratio in a grid of points across the entire Homunculus Nebula surrounding the peculiar, massive star η Carinae. The data cover the wavelength range 420–1000 nm. Included are parts of the outer nebulosity dating from a prehistoric ejection episode. At a spatial resolution of about 1 arcsec we find dramatic differences in emission Ime ratios and profiles, sometimes in adjacent resolution elements.

Plots of periods against (25μm – 12μm) colour of OH/IR stars suggest that four IRAS sources, that have been associated with known OH/IR stars, either provide anomalous identifications, or are weak rather than regular variables. It is argued here that only one of these cases is an association error. OH15.7+0.8 and OH37.1–0.8 are the new proto–planetary nebula candidates.

We present high-resolution absorption measurements (R ~ 150 000) of the interstellar Na I D-lines at 5890 Å observed towards 46 early-type stars. The distance to these stars ranges from 20–200 pc, allowing a probe of the local interstellar medium (LISM). The velocity structure, velocity dispersions and column densities of the various cloud components have been derived using an absorption line-fitting analysis. Sodium column densities have been determined for 23 of the 46 target stars. No sodium absorption was detected towards any of the stars with distances < 43 pc. Such null results imply a corresponding hydrogen column density limit, N(H), of ~ 2.5 × 1018cm−2 in many directions in the LISM. For three exceptionally vacant lines of sight (to β CMa, 36 Lyn and η Hya) this limit of low hydrogen column density can be placed out to a much further distance of > 150 pc.

We have plotted the distribution of sodium column density in the LISM for a total of 118 stars in the form of three galactic maps. These maps qualitatively show that the present picture of the LISM, in which the first 50 pc is essentially free of dense clumps of neutral gas, is correct. Our map of sodium columns for stars with distances > 100 pc shows that the region within the galactic quadrant defined by 200° < l < 270° shows a conspicuous absence of any significant concentration of neutral gas. This region will be a prime direction of study for forthcoming soft X-ray and extreme ultraviolet satellite experiments.

This paper discusses the spatial distribution of M supergiant stars in the Galaxy using infrared data from IRAS.

We present the results of an examination of low-resolution IUE spectra of Galactic planetary nebulae in an effort to determine the occurence of stellar winds in their central stars. Our analysis confirms the results obtained in previous studies.

There is growing evidence for the notion that large grains are an important constituent of the interstellar medium. It has been found to be necessary to invoke the presence of large grains (of radius a > 1.0 μm) in a number of circumstellar shells, including those around Eta Carinae, and some late type giants and supergiants. Most recently, as a result of IRAS observations, the same idea has been used in the interpretation of the extensive optically thin disks found around some young early type stars. It is important to establish size constraints on these grains, so as to determine better the probable mix of interstellar grains. Previous work on AG Carinae suggested merely that the grains in the circumstellar shell need to be larger than 1 μm, but gave no information regarding the maximum size which would be acceptable. In this paper, we explore the question of the characteristic size of the dust grains in the AG Carinae shell, by fitting the spatially integrated model energy distribution to observations over the wavelength range 360 nm–100 μm, and conclude that silicate grains of radius ~ 1.0 μm give a satisfactory fit to the spectrum and angular distribution, but that grains appreciably larger or smaller than this radius are unsatisfactory.

This paper discusses the accretion wave phenomenon as a generator of the Great Galactic Ring and the mechanism for forming discontinuities in interstellar gas flows.

We have carried out an extensive survey of Hα emission stars in the Orion region over an area of about 100 deg2. We present the results for the areas A-0975 and A-0976 of about 25 deg2 each.

In our study of the extended supernova remnant G54.4–0.3, we find a CO emission shell at about 40km s−1 radial velocity, in striking alignment with the radio continuum shell. The correspondence in position and size argues strongly for a physical connection, and allows derivation of the kinematic distance as well as the mass and density of the CO shell. The correlation with an OB association supports the value derived for the kinematic distance. Model calculations suggest that the formation of the CO shell results from a stellar wind and that the supernova remnant has expanded into the wind bubble located inside the shell.

Observations of five cepheids in Crux are described and annual epochs of maxima presented. The O–C diagram of S Crucis shows changes between two alternative periods. The observing method appears suited to sites with only a limited number of hours available.

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 authors analyse four high-dispersion IUE spectra of HD 184279 observed in 1979 and 1982.

This paper briefly discusses the Aten, Apollo and Amor asteroid types (collectively referred to as AAAs), their perihelion distribution and orthogonal motion. There are 90 objects in these classes: 6 Atens, 46 Amors and 38 Apollos. The maximum distance to the ecliptic plane of each class follows an exponential function.

Pulsar rotation measures have been used to investigate the structure of the local Galactic magnetic field. The Galactic field is found to be concentrated in the spiral arms and hence to be a spiral field. From the pulsars within 2kpc of the Sun, the field in the local spiral feature was modelled with Gaussian profiles in altitude and azimuth. In this model the field has a peak strength of 4.3 ± 0.2 μGauss directed towards Galactic longitude l = 73°±6°.

We have simulated numerically the hydrodynamic cooling process after the maximum phase of a solar flare with improvements on the chromospheric radiative loss and the resolution of the transition region, together with the introduction of the mechanism of chromospheric heating by coronal soft X-rays. The main results are as follows:

1. 1. At the early stage of the gradual phase, thermal conduction maintains chromospheric evaporation, but with the cooling of the atmosphere, chromosphere evaporation decreases gradually.

2. 2. In most of the gradual phase, the velocity is smaller than 40km s−1 in the corona and 4km s−1 in the chromosphere.

3. 3. From the middle stage of the gradual phase, the coronal atmosphere appears to have a quasi-periodic oscillation. The period is about two minutes, and the amplitude of velocity is within ±20km s−1.

4. 4. The transition region continues to move downward at first and then changes very slowly for quite a long time. The upward motion of the transition region takes place only at the latest stage, when the atmosphere cools below the quiet-Sun case.

5. 5. In contrast to the changes of temperature, the density of the corona does not seem to vary until the violent descent of coronal material takes place at the end of the gradual phase.

6. 6. The coronal part cools mainly by thermal conduction, while the chromospheric part cools by radiative loss. With our initial model, it takes about 25 minutes for cooling from the maximum phase to nearly the quiet-Sun case.

7. 7. The soft X-ray heating of the chromosphere seems to be of negligible importance in our calculations, but if the coronal density is greater than 1011 cm−3 at the maximum phase of the flare, the soft X-ray heating may play some role in the gradual phase.

8. 8. At the latest stage of the gradual phase, the atmosphere remains dense and at low temperature. As a further consequence, it would evolve into a post-flare loop.

It has been suggested that diffuse X-ray sources observed in globular clusters may arise in bow shocks formed by the interaction of intracluster gas with a tenuous halo medium. This paper presents a study both of the cluster space motions and of the energetics of any possible bow shocks which would seem to rule out this hypothesis.

A photometric and spectroscopic survey of many of the cool H-deficient Carbon (HdC) stars, including the R Coronae Borealis (RCB) stars, has been undertaken. For the RCB stars we have data on both the low amplitude photometric variations at maximum light and the major declines, the latter being the most distinguishing feature between the RCB and HdC stars.

The photometric data at maximum light have been analysed using the Lomb-Scargle Fourier method, which has revealed many significant periodicities. From estimates of the temperature of these stars, an observational period-temperature diagram can be compared with theoretical models. These models have also enabled us to determine the evolutionary lifetime of these stars for comparison with observational parameters, e.g., period changes.

Over the last several years we have photoelectrically covered the declines (and the recovery from some of these declines) of a number of RCB stars, from which we have been able to characterise two extreme types of decline behaviour. In addition, we have for the very first time spectroscopically recorded the initial decline phase of one (the prototype, R CrB) of these stars.

The time and spatial distributions of the ‘energy flare indices’ which have been observed since Cycle 21 are analysed and 13 hot spots of energy flares during this period are given in this article. These active regions of the ‘hot spots’ appear repeatedly where there erupted the energy flares accounting for 63.2 per cent of the total indices. The characteristics of the hot spots of the energy flares and the relationship between the hot spots and the evolution of the large-scale magnetic fields are also further discussed in this paper.