Following a brief discussion of the possibilities offered by X-ray spectroscopy at various values of resolving power (E/ΔE), the spectroscopic capabilities of a number of future missions are presented. The possible roles of Charge Coupled Devices (CCD’s), Microcalorimeters, Diffraction Grating and Bragg Crystal Spectrometers are then evaluated.

We have found from line-of-sight integration of scattered light and thermal emission that the appearance of a hump in the F-corona, which was observed in the near-infrared wavelengths by Peterson (1969) and MacQueen (1968), is very sensitive to the change of size distribution of circumsolar dust grains. Namely, the size distribution affects the balance of scattered sunlight and thermal emission. We suggest that a temporal variation in the size distribution of circumsolar dust grains is a potential origin of the temporal variation of the hump structure observed in the F-corona.

After the report on flare stars presented by Ambartsumian and the author (1971) at the last Bamberg Colloquium, some success has been achieved in the study of these interesting objects.

Optical observations of stellar flares with high time-resolution undoubtedly proved the explosive character of this phenomenon and the non-thermal nature of the radiation that appears at least at the beginning of the flare. Parallel optical and radio observations of flares in stellar aggregates complicated the interpretation and showed how far we are from an understanding of the physical nature of this phenomenon. Finally, new optical observations of stellar flares in aggregates of different age confirmed the evolutionary significance of this stage in the life of a star and led to the study of certain regularities in the evolution of flare stars.

We have observed a complete sample of 21 nearby (D < 70h−1Mpc) Fanaroff & Riley Type I galaxies with HST/WFPC2 and detected dust disks and lanes in 19 of them. The radio jets are roughly perpendicular to the dust which is used to constrain the Doppler boosting factors of the radio jet and cores. The VLBA core flux correlates with the central Hα+[NII] flux which might indicate that the VLBA core is dominated by an isotropic component. Twelve galaxies show nuclear optical sources. We discuss various possible origins for this emission.

A new Edition of the Asiago Catalogue of QSOs (Barbieri et al. 1982) is available on magnetic tape. It contains essentially all the information of the previous editions updated with the papers published before Dec.31, 1984. The catalog should be essentially complete to that date in respect to objects having slit spectra (2330 objects), while it is seriously incomplete regarding candidates discovered by objective prism or grism/grens surveys after 1982 (279 such objects included in the present version).

Sandage (1986) showed what the star formation rate (SFR) of galaxies of different Hubble type might look like. His curves are based on the study of Gallagher et al. (1984), who determined the SFR at three different epochs of galactic evolution. Sandage's figure establishes a connection of SFR and Hubble type but, as was already mentioned by Sandage, it “contains no physics”. In order to explore the background of this connection, however, it is necessary either to improve the observations or to model the evolution of galaxies self-consistently. However, the results of modelling the SFR are not reliable, if simplified models are used, which only describe some structural properties of galaxies. It is necessary to apply self-consistent models which take into consideration all relevant interaction processes between the gaseous and stellar components of a galaxy. Such models can be checked by comparison with observations like density and abundance distributions, star-gas content, velocities, velocity dispersions, mass-luminosity relations and age distributions of stars. A detailed model will show, whether the initial conditions, the feedback mechanisms during the evolution or the environment determine the evolution of a galaxy.

Star-formation is one of the main processes that shape galaxies, and together with black-hole accretion activity the two agents of energy production in galaxies. It is important on a range of scales from star clusters/OB associations to galaxy-wide and even group/cluster scales. Recently, studies of star-formation in sub-galactic and galaxy-wide scales have met significant advances owing to: (a) developments in the theory of stellar evolution, stellar atmospheres, and radiative transfer in the interstellar medium; (b) the availability of more sensitive and higher resolution data; and (c) observations in previously poorly charted wavebands (e.g. Ultraviolet, Infrared, and X-rays). These data allow us to study more galaxies at ever-increasing distances and nearby galaxies in greater detail, and different modes of star formation activity such as massive star formation and low level continuous star formation in a variety of environments. In this contribution we summarize recent results in the fields of multi-wavelength calibrations of star-formation rate indicators, the Stellar Initial Mass function, and radiative transfer and modeling of the Spectrale Energy Disrtributions of galaxies.

We have been searching the northern sky for ultra-narrowband carriers of intelligent extraterrestrial origin at 21cm wavelength. The dual-polarization 65,536-channel receiver has a resolution bandwidth of 0.03Hz, matched to the Drake-Helou spreading of the interstellar medium. This maximizes signal/noise ratio, and simultaneously rejects carriers of terrestrial origin. The results of 15 months of observation are summarized.

Detection of narrow ( δλ< 0.5 A ) absorption features in C IV at λ λ 1548 and 1550 have been made in the spectra of 4 late B dwarfs within 200 pc of the sun; the Si IV doublet at λ λ 1393 and 1403 shows up in two of them. We argue that it is difficult to account for the strengths, widths, shapes , and C IV/Si IV ratios in terms consistent with a circumstellar origin except possibly for an asymmetric C IV component in one star (HD 135037). The most probable source is “semi-torrid” gas (cf. Bruhweiler et al. 1980) in the 50,000 K range forming the interfaces between cooler H I clouds and the ambient medium at coronal temperatures. Our technique, using late B rapid rotators, is useful for LISM probing of this kind.

We probe gravitational clustering in N-body simulations using geometrical descriptors sensitive to ‘connectedness’: the genus curve, percolation and shape statistics. As gravitational clustering advances, the density field in N-body simulations shows an increasingly pronounced departure from Gaussianity reflected in the changing shape of the percolation curve and the changing amplitude and shape of the genus curve. We feel that both genus and percolation curves provide complementary probes of large scale structure topology and could be used to discriminate between models of structure formation and the analysis of observational data such as galaxy catalogs and MBR maps. The filling factor in clusters & superclusters at percolation is small indicating that matter is more likely to lie in filaments and pancakes. An analysis of ‘shapes’ in N-body simulations has shown that filaments are more pronounced than pancakes. To probe shapes of clusters and superclusters more rigorously we propose a new shape statistic which does not fit isodensity surfaces by ellipsoids (as done earlier). Instead our shape statistic is derived from fundamental properties of a compact body such as its volume V, surface area S, integrated mean curvature C, and connectivity (characterized by the Genus). The new shape statistic gives sensible results for topologically simple surfaces such as the ellipsoid, and for more complicated surfaces such as the torus.

The 30-inch Thaw Refractor of the University of Pittsburgh's Allegheny Observatory has been completely rebuilt. Changes include a new objective lens, a new detector system, and computer control and data acquisition. With an observational accuracy exceeding one-thousandth of an arc second, the new system will greatly expand the domain of astrometric research.

We present initial results of a survey of the FUV spectra of disk-accreting cataclysmic variables obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE).

FUSE covers the 905 - 1188 Å range at spectral resolutions ≃0.1 Å. To date, FUSE has observed more than 65 cataclysmic variables (CVs). Publicly-available data include observations of 11 dwarf novae (DN), 15 non-magnetic novalikes (NLs), 7 intermediate polars and DQ Her stars, at least 15 polars, and 4 super-soft X-ray binaries.

The question posed by the title is not yet conclusively resolved. Nonetheless, determinations of the lunar tidal acceleration based on dynamical time scales are now in reasonable accord with one another, whether based on the transits of Mercury, ancient eclipse observations, ocean tide models, or artificial satellite observations; these give a purely tidal component of −28.8 ± 1.5 “/cy2. Lunar occultations and laser ranging now give concordant results for the total anomalous acceleration of about −22.8 ± 1.5. The difference in these results gives an acceleration of possible cosmological origin of ṅ/n = +3.5 ± 1.2 × 10−11 per year, which is also consistent with very preliminary planetary radar studies. If interpreted in the scalar covariant cosmology of Canuto and Hsieh, this implies that Ġ/G = (−6.9 ± 2.4) × 10−11 per year, if measured in atomic time, but zero if measured in dynamical time. The implications for relativity and cosmology are discussed briefly in the paper, scheduled for the Astrophysical Journal issue of 1 September 1981.

The evolution of the orbits of 19 asteroids of particular interest has been studied over the interval 1660–2060, perturbations by Venus to Pluto being taken into account. Information was obtained about the encounters with Venus, the Earth, and Mars. A few approaches of Hidalgo to Jupiter were noted. In distinction to the orbits of short-period comets, the orbits of the 19 asteroids are stable throughout the 400-yr interval.

Crystalline silicate dust particles have been found in some comets, though progenitors of those dust particles are thought to be amorphous. Here, the origin of the crystalline particles was investigated based on the shock-wave heating mechanism. We find that appropriate shock waves can crystallize amorphous dust particles and conditions of these shock waves (shock velocity and pre-shock gas density) are clarified.

The gas density in the solar nebula and the shock velocity that may be induced in comet forming regions by some mechanisms were discussed. It was suggested that comets formed in a region closer than about 20 AU to the Sun can contain the crystalline particles, whereas comets formed in a further region can hardly have them.

In δ Scuti star models the photometric amplitudes and phases exhibit a strong dependence on convection, which enters through the complex parameter,f, that describes the bolometric flux variation. We present a new method of extracting l and f from multi-colour data and apply it to several δ Scuti stars. The inferred values of f are sufficiently accurate to yield a useful constraint on models of stellar convection.

It was shown by Maitzen & Pavlovski (1989) that a majority of λ Bootis stars stand out by negative Δα indices. Using this as detection tool, three candidate stars with λ Bootis characteristics are picked up in open cluster Praesepe.

Galactic D/H evaluations from observations completed in the far UV with first the Copernicus satellite then followed by IUE and the GHRS on the HST studies already suggest that D/H variations may be present in the interstellar medium. More recent IMAPS (the Interstellar Medium Absorption Profile Spectrograph) observations confirm that conclusion while new STIS (which replaced the GHRS on board HST) studies seem to indicate the contrary. The situation is discussed here.

Hopefully FUSE (the Far Ultraviolet Spectroscopic Explorer, launched the 24th of June 1999) will give access to the D/H ratio in many different galactic sites. This will help us reach a better global view of the evolution of that key element, and thus better constrain any evaluation of its primordial abundance.

We present the first sub-kpc (∼ 0.7 ≈ 0.8 kpc) resolution 12CO(1–0) observations of the ISM in the host galaxy of the QSO I Zw 1 which were obtained with the BIMA mm-interferometer in its A configuration. The measurements, which are part of a multi-wavelength study of I Zw 1, will allow comparison of the ISM properties of a QSO host with those of nearby galaxies and place constraints on galaxy formation/evolution models. Our maps of the 12CO(1–0) line emission from the host galaxy of a QSO show a ring-like structure in the circumnuclear molecular gas distribution with a radius of about 900 pc. The presence of such a molecular gas ring was already predicted from earlier lower angular resolution PdBI observations (Schinnerer, Eckart, & Tacconi 1998). A first comparison of the BIMA data with new PdBI 12CO(2–1) observations with 0.9 angular resolution shows variations in the excitation conditions of the molecular gas in the innermost 3 comprising the nuclear region of I Zw 1.