Recent, high sensitivity, HI observations of nearby spiral galaxies show that their thin ‘cold’ disks are surrounded by thick layers (halos) of neutral gas with anomalous kinematics. We present results for three galaxies viewed at different inclination angles: NGC 891 (edge-on), NGC 2403 (i=60°), and NGC 6946 (almost face-on). These studies show the presence of halo gas up to distances of 10-15 kpc from the plane. Such gas has a mean rotation 25-50 km s−1 lower than that of the gas in the plane, and some complexes are detected at very high velocities, up to 200-300 km s−1. The nature and origin of this halo gas are poorly understood. It can either be the result of a galactic fountain or of accretion from the intergalactic medium. It is probably analogous to some of the High Velocity Clouds (HVCs) of the Milky Way.

This paper summarizes some recent results obtained with the solar radio-spectroscope at Dapto (Sydney), which has been in operation since 1952. The basic instrument is a receiver which sweeps through the frequency range 40–240 Mc./s. every half a second. Each spectrum is displayed as an intensity-modulated line, and successive spectra are recorded photographically on continuously moving film to give a dynamic record of the spectrum.

Light fluctuations have been found in all 22 QSOs studied by measurement of plates from the Harvard collection, which cover the last eighty years. The conclusions of this study are: (i) There appear to be at least three general classes of variation: (a) erratic, small-amplitude variations, (b) erratic, large-amplitude variations, and (c) slow quasi-periodic variations, e.g. as in 3C 273; (ii) No significant differences were detected between the rates of rise and decline of luminosity; (iii) Definite secular trends over at least 50 years were found in 5 QSOs; (iv) No simple clearcut periods greater than one year have been found; (v) There may be a trend of decreasing amplitude of fluctuations in apparent magnitude with increasing luminosity.

This review summarises those observations which relate to the existence of dust in planetary nebulae. The most direct evidence for dust, namely infrared emission by grains, is considered in Section 2. Section 3 describes a variety of optical and ultraviolet observations which bear more indirectly on the properties of the dust, while Section 4 discusses the power sources of the observed infrared emission. The peculiar nebulae A 30 and A 78 are considered in Section 5, and Section 6 concludes with a discussion of the various infrared features which have been observed in emission from planetary nebulae.

The ζ Herculis system is one of the closest well-kown binaries. A tentative modelling shows that though the brighter star is easily described with a mass compatible with the observed one and an age of approximately 3.4 billion years, difficulties arise for the secondary, which plea for more precise observations.

Collisions of icy objects play a major role in the outer solar system. The purpose of this investigation is the experimental study of plasma production by dust impacts on icy surfaces. Impact speeds ranged from 3 to 60 km/s. It was found that the dominant ion species which were released are both positive and negative water clusters. The impact charge yield from icy surfaces is approximately a factor 100 below that from previously studied gold surfaces.

A computer model for isolated disks of stars is used to study the self-consistent motion of large numbers of point masses as they move in the plane of the galactic disk. The Langley Research Center's CDC 6600 computers are used to integrate the equations of motion for systems containing from 50000 to 200000 stars. The results are presented in the form of a motion picture.

We discuss the origin of hot hydrogen-deficient post-AGB stars. Evidence is growing that the “born-again AGB star scenario” as a consequence of a late He shell flash cannot explain the diverse observations. Analyses of the stars and their associated planetary nebulae suggest that the H-deficiency is not formed during the second post-AGB phase but already while the star is still on the AGB. There are even hints that the H-deficiency can occur before the first departure from the AGB.

The early results on astrochemistry from the Cores to Disks (c2d) Legacy program are summarized. The c2d program focuses on the formation of low-mass stars in nearby (within about 300 pc) clouds. Spectroscopy with IRS includes the following topics: ices seen against background stars, in protostellar envelopes, and in disks; grain growth and mineralogy, PAHs, and gas in circumstellar disks.

Three pulsar timing arrays are now producing high quality data sets. As reviewed in this paper, these data sets are been processed to 1) develop a pulsar-based time standard, 2) search for errors in the solar system planetary ephemeris and 3) detect gravitational waves. It is expected that the data sets will significantly improve in the near future by combining existing observations and by using new telescopes.

The interstellar medium constitutes a physically and chemically complex component of galaxies and is important in the cycle of matter and the evolution of stars. From various spectroscopic clues we now know that the interstellar medium is rich in organic compounds. However, identifying the exact nature of all these components remains a challenge. In particular the identification of the so-called diffuse band carriers has been alluding astronomers for almost a century.

In recent decades, observational, experimental and theoretical advances have rapidly lead to renewed interest in the diffuse interstellar bands (DIBs). This has been instigated partly by their perceived relation to the infrared aromatic emission bands, the UV extinction bump and far-UV rise, and the growing number of (small) organic molecules identified in space.

This chapter gives an overview of the observational properties and behaviour of the DIBs, and their presence throughout the Universe. I will highlight recent progress in identifying their carriers and discuss their potential as tracers and probes of (extra)-Galactic ISM conditions.

Though there are a variety of astronomy sonification software packages, none of them shown high granularity evidence of having been designed with a user-centric focus. SonoUno is a sonification package created taking into account the user from the beginning, and incorporates end user contact feedback for continuous improvements to the software. In this contribution, SonoUno user cases are presented with the soft corresponding updates, as well as the first description of a recent web page development.

The dependence of the solar cycle duration, T, on the 3 years averaged module of the large-scale sunspots magnetic fields (30-60 arcsec), Bsp index, was investigated on the base of about 10,000 visual observations conducted during last eight (16-23) cycles. It was found that the duration T of the investigated cycles linearly depends on the index Bsp of the magnetic fields observed during 3 years on decline phase of the solar cycle (second, third and fourth years after solar maximum Tmax). Namely, the duration of the cycles T was varied between 9,5 and 12,5 years, when the magnetic index Bsp was ranged from 2450 to 2600 G. An explanation for this dependence is proposed within the framework of non-linear αΩ- dynamo model. We found the following equation for the dependence of solar dynamo-period on magnetic index: T ≈ Bsp3/2. Therefore, the large observed index Bsp, the longer calculated period T.

Current and forthcoming cosmological data analyses share the challenge of huge datasets alongside increasingly tight requirements on the precision and accuracy of extracted cosmological parameters. The community is becoming increasingly aware that these requirements not only apply to the central values of parameters but, equally important, also to the error bars. Due to non-linear effects in the astrophysics, the instrument, and the analysis pipeline, data covariance matrices are usually not well known a priori and need to be estimated from the data itself, or from suites of large simulations. In either case, the finite number of realisations available to determine data covariances introduces significant biases and additional variance in the errors on cosmological parameters in a standard likelihood analysis. Here, we review recent work on quantifying these biases and additional variances and discuss approaches to remedy these effects.

We summarize the fifty-year concerted effort to place the “activity” of the Sun in the context of the stars. As a working definition of solar activity in the context of stars, we adopt those globally–observable variations on time scales below thermal time scales, of ~105 yr for the convection zone. So defined, activity is dominated by magnetic–field evolution, including the 22–year Hale cycle, the typical time it takes for the quasi-periodic reversal in which the global magnetic–field takes place. This is accompanied by sunspot variations with 11 year periods, known since the time of Schwabe, as well as faster variations due to rotation of active regions and flaring. “Diagnostics and indices” are terms given to the indirect signatures of varying magnetic–fields, including the photometric (broad-band) variations associated with the sunspot cycle, and variations of the accompanying heated plasma in higher layers of stellar atmospheres seen at special optical wavelengths, and UV and X-ray wavelengths. Our attention is also focussed on the theme of the Symposium by examining evidence for deep and extended minima of stars, and placing the 70–year long solar Maunder Minimum into a stellar context.

We present the first results of the observations of the supernova remnant RX J1713.7–3946 (also known as G347.3–0.5) obtained with the EPIC instrument on board the XMM-Newton satellite. We show a 5-pointings mosaiced image of the X-ray synchrotron emission. We characterize this emission by mapping its spectral parameters (absorbing column density NH and photon index γ). The synchrotron spectrum is flat at the shock and steep in the interior of the remnant. NH is well correlated with the X-ray brightness. A strong NH is found in the southwest rim of RX J1713.7–3946. We suggest that the SNR is interacting with a HI region there.

Some 6 km. of high-speed (Brush) records of the solar radio radiation at 200 Mc./s. made at Cornell University by Ch. L. Seeger in 1949 and 1950 have been kindly put at our disposal. They were made with a paper speed of 0·5 cm./sec., sometimes with 2·5 cm./sec. The response time of the recording pen was 0s·02. Some records have been made simultaneously at 205 Mc./s. and at 200 Mc./s. This paper gives some results of a discussion of these records. The properties that were studied are: the clustering tendencies among the radio-pips, their band-widths, the echo-phenomena and the duration of the pips.

We performed spectroscopy of globular clusters associated with NGC 1399 and measured radial velocities of about 450 clusters, the largest sample ever obtained for dynamical studies. In this progress report, we present the sample and the first preliminary results. Red and blue clusters have slightly different velocity dispersions in accordance with their different density profiles in the case of a spherical and isotropic model. We then measure a constant circular velocity of 422 ± 20 km/s, which agrees well with that of the inner luminous component.

The advantages of studying samples of supernova remnants in external galaxies will be discussed. A summary of how the remnants can be used to infer starformation rates in starburst galaxies will be given, as will the use of these remnants to probe the interstellar medium of these galaxies on parsec scales. Widefield EVN and Global VLBI measurements of remnants in the nearby starburst in M82 will be described in detail, and recent expansion velocity measurements described. The similarity between the strongest compact source in M82 and the objects recently discovered in Arp220 will be noted. The sensitivity limitations of this work will be discussed and the prospects for studies of more distant objects using Square Kilometer Array considered.