It seems hard to realise, today, that pulsars were totally unknown at the time of the last General Assembly. The discovery of pulsars dates from November 28th, 1967, when the first pulses were recorded from the source now known as CP 1919. Since then we have witnessed an astonishing phase of activity, amongst observers and theoreticians alike, which may be unique in the history of astronomy. Now, with at least 50 pulsars in the catalogues, we are in possession of a wealth of information about these remarkable sources. My aim tonight is to outline the observational evidence which leads us to the physical nature of pulsars. I shall happily leave to Professor Ginzburg the far more difficult task of weaving these strands into a logical pattern and devising a model to account for what is observed.

In a series of previous papers (ROSINO, 1966; ROSINO-PIGATTO, 1969; PIGATTO-ROSINO, 1971) we have given some results on the systematic search of flare stars in clusters and associations carried out at Asiago with the 90—67 cm Schmidt telescope. We have employed for the survey Kodak 103 a—o or oa—o plates without filter covering a field of 25 square degrees, the flares having been searched with the method of multiple exposures.

Properties of the quasi-coherent oscillations in the extreme ultraviolet flux of the dwarf nova SS Cygni are described.

The Barium stars are reviewed in terms of their known binary nature and their quantitative abundance peculiarities. It is concluded that the most likely explanation of the 12C and s-process overabundances observed in the Barium stars is mass transfer from a companion, which is now a white dwarf, but was once a 4He-burning thermally-pulsing asymptotic giant branch star.

Late-type secondaries in Algol binaries are rapidly rotating convective stars and thus should be chromospherically active (CA). They are examined with respect to observational manifestations which characterize already known CA stars: Ca II H and K emission cores, photometric variability attributable to starspots, soft x-ray emission, non-thermal radio emission, ultraviolet and infrared excess, and alternating period changes. The conclusion is that they can be regarded as another class of CA stars. In most respects they are literally indistinguishable from other CA stars. Ca II H and K emission cores are observed in the lobe-filling component of six semi-detached binaries: U Cep, RT Lac, RV Lib, AR Mon, S Vel, HR 5110. Alternating period changes are shown to occur only in Algols containing a late-type (convective) star. It is proposed, therefore, that the Matese-Whitmire mechanism explains these changes. Specifically, the interval from one increase (or decrease) to the next can be equated with the star’s magnetic cycle. Cycle lengths for 31 stars, derived in this way, range between 7 years and 109 years, with a median of 50 years.

Studies of brown dwarfs as a distinct galactic population have been largely pioneered by dedicated, vast-area surveys at deep optical and near-infrared wavebands. The Two Micron All Sky Survey has, because of its full-sky coverage and depth, been the most successful at providing new targets for further study. The author briefly reviews some of the ways in which 2MASS data have been used by brown dwarf researchers. One of the by-products – namely the 2MASS Team's follow-up spectroscopy of brown dwarf candidates – is potentially valuable as a scientific resource itself and is also being released to the public.

Recent observations demonstrate that dwarf galaxies in clusters, despite their faintness, may be a critical galaxy type for understanding the physical processes behind galaxy formation. Dwarfs are the most common type of galaxy and are particularly abundant in rich galaxy clusters. The dominate model for explaining the formation of these systems thorough Cold Dark Matter models is that the bulk of their stellar mass formed early, and within their present environments. Recent results however suggest that some dwarfs appear in clusters after the bulk of its members form, a scenario not predicted in standard hierarchical structure formation models. Many of these systems appear to be younger and more metal rich than dwarfs in lower density areas, suggesting they are possibly created by a tidal process induced by the cluster. Several general galaxy cluster observations, including steep luminosity functions and the origin of intracluster light, are natural outcomes of these processes.

We present observational evidence that NGC 6543 produced a jet of cosmic rays that irradiated the Earth recorded as cosmogenic10Be found ice cores. This identification shows that the jet was accompanied by a magnetic field of sufficient strength to travel 220pc and retain evidence of the celestial coordinates of the source object.

Rotation curves of high luminosity spiral galaxies are flat, to distances as great as r=49 kpc. This implies a significant mass at large r. Rotational velocities increase about 20 km/s across a spiral arm, as predicted by the density wave theory. By analogy, it is suggested that our Galaxy has a flat rotation curve out to r∼60 kpc, with V ∼ constant at near the solar rotational velocity, and m ∼7×1011 m⊙. Values of A and B imply that the sun is not located in a spiral arm.

Angular momentum transport in protostellar disks can be achieved by the action of a large scale magnetic field that runs vertically through the disk. The magnetic field centrifugally drives material from the disk surfaces into a wind, initiating a bipolar outflow. One apparent difficulty for this model is that the conductivity of the disk is extremely low in the inner 0.1–10 AU of the disk, where grains are the dominant charge carriers. Near the midplane, charged grains are unable to drift through the neutral gas and there is negligible coupling between the magnetic field and the disk material.

However, the removal of angular momentum and acceleration of a wind by a magnetic field can still take place in the surface layers of the disk where the gas conductivity increases dramatically. Solutions to the multifluid MHD equations for the vertical structure of a disk at a particular radius are presented. Most of the disk material sits in hydrostatic equilibrium and does not interact with the magnetic field running vertically through it. Near the disk surfaces, the coupling between the magnetic field and disk material is sufficient to initiate an outflow from the disk surface.

A statistical criterion for stopping CLEAN procedure is proposed. The criterion is called WIC and an estimator of Kullback-Leibler information quantity which is a measure of the goodness of statistical models. A numerical example is given.

In this talk I give a short overview of models for spectral lines in Be stars disks which I think are quite instructive. I then examine the arguments for my own model assumptions and discuss selected topics concerning radiative line transfer calculations in three dimensions. We show that symmetric Hα emission lines of Be stars can be understood in terms of Keplerian disks. It is also demonstrated that one-armed global disk oscillations provide the best available solution to understand the long-term V/R variations in Be star emission lines.

We present a dust radiative transfer analysis of the edge-on spiral galaxy NGC 5908. In our previous analysis, it was found that the standard assumption of a double-exponential dust distribution resulted in a poor fit. We investigate the possibility of the dust being distributed in one or more rings. The parameters are constrained using FitSKIRT, a code used to automatically determine the best fitting radiative transfer model given a set of observations. We discuss the possible implications of this dust distribution on the predicted spectral energy distribution.

Planetary exploration is resulting in the creation of new archaeological sites, material and debris on planets and their moons, and in various orbits round the Earth, Mars, the Sun etc. The main off-Earth bodies with sites so far are the Moon and Mars. Although thousands of archaeological sites on Earth are protected for their heritage value, no sites off-Earth are properly protected as yet. Sites off-Earth need to be ranked for their comparative heritage significance and protocols developed for the conservation and protection of the more significant sites and artifacts, before specimens are collected and returned to Earth in an uncontrolled (from heritage points of view) manner. A new United Nations Space Heritage Treaty is needed, or at least appropriate IAU and WAC (World Archaeological Congress) protocols agreed by the various parties concerned. The UN Outer Space Treaty 1967 is very out of date and a product of the Cold War.

Statistical studies of active galaxies (both AGN and Starburst) using large multi-wavelength data are presented, including new studies of Markarian galaxies, large sample of IR galaxies, variable radio sources, and large homogeneous sample of X-ray selected AGN. Markarian survey (the First Byurakan Survey) was digitized and the DFBS database was created, as the biggest spectroscopic database by the number of objects involved ( ~ 20 million). This database provides both 2D images and 1D spectra. We have carried out a number of projects aimed at revealing and multi-wavelength studies of active galaxies among optical, X-ray, IR and radio sources. Thousands of X-ray sources were identified from ROSAT, including many AGN (52% among all identified sources). IRAS PSC/FSC sources were studied having accurate positions from WISE and a large extragalactic sample was created for further search for AGNs. The fraction of active galaxies among IR-selected galaxies was estimated as 24%. Variable radio sources at 1.4 GHz were revealed by cross-correlation of NVSS and FIRST catalogues using the method introduced by us for optical variability. Radio-X-ray sources were revealed from NVSS and ROSAT for detection of new active galaxies. Big Data in astronomy is described that provide new possibilities for statistical research of active galaxies and other objects.

This paper reviews some recent results obtained from multi-wavelength studies that extend from white light to radio. Special emphasis is given to radio observations, which can be used to determine emission mechanisms and to trace electron propagation paths and plasma motions. Multi-wavelength comparisons have been found to be essential when analysing flare- and CME-related eruptions, but significant results have also been obtained in ‘quiet’ Sun studies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The preliminary results of the CCD search for variable stars in the very young open cluster NGC 6823 are presented. About ten new variable stars were discovered. The most interesting finding is that of the two pre-main sequence (PMS) δ Scuti-type variables. Because the evolutionary rate of period change is large at the PMS stage, these stars could be used in the future for testing it observationally.

To investigate the accuracy of the determination of terrestrial refraction from reciprocal zenith angles and astronomical latitudes and longitudes at both ends of a line a test net with lines from 4 km to 23 km was observed and three dimensionally adjusted. As the measurements of the zenith angles were repeated every hour 40 times in an average the adjusted values were taken as a substitute for the true values. It is shown, that the mean refraction coefficient k, which is changing from k = 0.10 at day up to k = 0.34 at night, and the corresponding refraction angle can be determined very accurately, if both angles are measured simultaneously. Observations with day light are better than observations in the night. For observations with day light the mean difference between the true refraction angle at the observation station and the mean refraction angle of the observed line was smaller than ± 1″ independent of the length of the line. That means that the mean deviation of the true effective refraction coefficient in the observation station and the mean refraction coefficient of the observed line was inverse proportional to the distance.

We performed a detailed spectroscopic analysis of the fullerene C60-containing planetary nebula (PN) Lin49 in the Small Magellanic Cloud (SMC). Lin49 is a C-rich and metal-deficient PN (Z~0.0006) and its nebular abundances are in agreement with the AGB model for the initially 1.25 M⊙ stars with the metallicity Z = 0.001. By stellar absorption fitting with TLUSTY, we derived stellar abundances, effective temperature, and surface gravity. We constructed the photoionization model with CLOUDY in order to investigate physical conditions of Lin49. The model with the 0.005-0.1 μm radius graphite and a constant hydrogen density shell could not fit the ~1-5 μm spectral energy distribution (SED) owing to the strong near-IR excess. We propose that the near-IR excess indicates (1) the presence of extremely small carbon molecules or (2) the presence of high-density structure surrounding the central star.

The existing data on the distribution of O and B stars, of optical and radio H II sources, of H I and of cosmic dust have been assembled for the Carina-Centaurus Section of the Milky Way, lII = 265° to 305°. The published data have been supplemented by recent photoelectric UBV data and new photographic material. Two Working Diagrams (Figures 9 and 10) of the Carina Spiral Feature have been prepared. The Feature is sharply bounded at lII = 282° and again at lII = 295° in the range of distance from 1.5 to 6 kpc from the sun. Its outer rim is observed from the sun almost tangentially to a distance of 8 kpc from the sun. The Feature is found to bend at distances greater than 9 to 10 kpc from the sun, a result shown by both radio H I and radio H II data.

Figure 9 presents our basic data for the stellar, gas and dust components of the Feature. The O and early B stars and the H II Regions are closely associated and within 6 kpc of the sun they are concentrated in the range 285° < lII < 295°. The distribution in longitude of H I is broader and spills over on both sides of the O and B and the H II peak distributions. Long period cepheids yield a concentration similar to that shown by O and B stars and H II Regions. The visual interstellar absorption between lII = 282° and 295° is represented by a value AV = 0.5 mag kpc−1, or less, applicable to distances of 4 to 5 kpc. Much higher absorption is present on the outside of the Carina Spiral Feature, 265° < lII < 280°, where total visual absorptions as great as 3.5 mags. are found at distances of the order of 2 kpc. Even heavier absorption is indicated for these longitudes at 4 kpc from the sun, thus suggesting that the heavy obscuration on the outside of the Carina Spiral Feature is a phenomenon of general structural relevance (see Figures 8 and 9). Only small values of AV are found at the inside of the Spiral Feature.

The Working Diagram (Figure 10) shows that the O and B star peak and the H II peak have a width of 800 parsecs (12°) at 4 kpc from the sun, whereas the H I width is at least 1500 parsecs at the same distance. The peak of the O and B star distribution and of the H II distribution lies at about 600 parsecs (8° at 4 kpc) within the outer edge of the spiral feature. The heaviest interstellar absorption is on the outside of the Feature.