The HRTS (High Resolution Telescope and Spectrograph) instrument is a high spectral (0.05 Å) and spatial (<1 arc sec) resolution spectrograph with a slit length of 900 arc sec on the solar disk (see Bartoe and Brueckner 1975, 1978). HRTS contains in addition a double grating, zero dispersion broadband spectroheliograph which images the spectrograph slit jaw plate (see Cook et al. 1983). The central wavelength is tunable by changing the grating geometry. Hα images are also photographed from the slit jaw plate image. HRTS has been flown four times as a rocket payload, and will fly in April 1985 as one of the solar experiments aboard Spacelab 2. The four rocket flights of the HRTS program have each been customized for a particular scientific objective. For the fourth flight, because the original hardware was utilized as the basis of the Spacelab HRTS, the opportunity was used to design and build a new rocket HRTS instrument specialized for observations at the solar limb. In this configuration the photographic speed was increased, a new curved slit was fabricated, and the spectroheliograph was modified for limb observations. The scientific observing program was a study of structure and short term temporal evolution at the limb, with a comparison of quiet and coronal hole areas.

For the purposes of this talk I will take “high resolution” to mean 1 milliarcsecond (mas). Only objects of high surface brightness when averaged over 1 mas are considered; as H. McAlister will discuss stellar applications, I will speak only about nonstellar applications.

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.

The identification and observation of planetary nebulae in the Andromeda galaxy (M31) and its companions provide a powerful means of studying their old stellar populations. The direct determination of chemical abundances and radial velocities for even the brightest individual old stars is impossible at the distance of M31. The strongest emission lines of planetary nebulae are as bright as the entire visual continuum of the most luminous giants. Consequently, spectrophotometry of planetary nebulae presently provides the only direct measure of chemical abundances, and, with the exception of globular clusters, the only radial velocity determinations for the old populations.

The planetary nebula NGC 6543 has been described (Curtis, 1918) as “quite irregular, of helical form”. Its high surface brightness and its dimensions (16′′ × 22′′ of arc) make it an ideal object for observation with the multislit technique used by Wilson (1950) to study other planetaries. In fact, had NGC 6543 been accessible to the 100-inch Mount Wilson Coudé, undoubtedly it would have been included in Wilson's survey. The interest in NGC 6543 arises from the fact that no information is available regarding the motions in a planetary nebula with some sort of helical appearance. The obvious question that arises in this respect is whether the nebular material is actually arranged in space on an open helix, rather than in a flat spiral. The related problems of its lifetime and stability also may be elucidated by studying in detail the internal motions.

We discuss the difficulties of forming earth-like planets in metal-poor environments, such as those prevailing in the Galactic halo (Pop II), the Magellanic Clouds, and the early universe. We suggest that, with fewer heavy elements available, terrestrial planets will be smaller size and lower mass than in our solar system (solar metallicity). Such planets may not be able to sustain life as we know it. Therefore, the chances of very old lifeforms in the universe are slim, and a threshold metallicty (90% solar?) may exist for life to originate on large enough earth-like planets.

In order to obtain the solar spectrum of the Mgii lines at 2795.5 Å and 2802.7 Å, we built a balloon instrument which consisted of a Cassegrain telescope, with an aperture ratio of F/20 and a focal length of 300 cm to give a solar image on the slit of a spectrograph. The theoretical spectral resolution is better than 10 mÅ. In the laboratory, we measured a spatial resolution of 10 μ in the image plane of the spectrograph, which corresponds to 1 arc sec in this mounting. During a balloon flight of 1969, April 30, which used a biaxial pointing system, we obtained a spatial resolution better than 10 arc sec, limited by the accuracy of the pointing system. Lastly, on 1970 June 24, the same instrument with a servosystem inside the telescope, was launched and spectral and spatial resolutions of 25 mÅ and about 3 arc sec, respectively, were obtained.

A series of VLBI surveys of complete samples of radio sources selected at 5 GHz (Pearson & Readhead 1988, hereafter PR; Xu et al. 1995 and references therein) has revealed that ≃ 10% of the objects are “Compact Symmetric Objects” (CSOs), in which high-luminosity radio emission regions are seen on both sides of the center of activity on scales less than one kiloparsec (Phillips & Mutel 1982; Readhead et al. 1984; Conway et al. 1992; Wilkinson et al. 1994). In order to be sure that an object is a CSO, either the center of activity must be pinpointed (Taylor et al. 1996) or compelling morphological evidence of symmetric structure must be found.

A brief review of the observational properties of evolved massive stars is presented. In the pursuit of clues for their rotation, formidable difficulties are encountered. At the same time, common features emerge between B[e] supergiants, Luminous Blue Variables and Wolf-Rayet stars. Several indications of rapid rotation are found, mostly indirect ones, in each class. It is shown that fast rotation can probably survive the mass loss events which characterize the late evolution of massive stars.

In this series of papers we report on an effort to deduce the morphology of the chromosphere and corona of AR Lacertae, an eclipsing RS CVn system (Hall 1976), via observations at UV, radio, and X-ray wavelengths during a complete orbital cycle. In another paper (Gibson, Walter and Basri 1982, Paper I), we present the observational data and general constraints on the morphology of the coronae. The full study will be published elsewhere (Walter, Gibson, and Basri 1982).

We present the most extensive, long-slit, high-resolution coverage of the complex planetary nebula (PN), NGC 7026. Ten spectra were acquired using the Manchester Echelle Spectrometer at San Pedro Martir Observatory in Baja California, Mexico, and each shows exquisite detail, revealing the intricate structure of this object. Incorporating these spectra into the 3-dimensional visualization and kinematic program, Shape, and using HST images of NGC 7026, we have produced a detailed structural and kinematic model of this PN. Knowledge of the 3-D structure of this nebula is relevant to understand the physics behind the extended X-ray emission in this object.

The 2dF Galaxy Redshift Survey is now complete, and the full data are public. 2dFGRS was the first survey to observe more than 100,000 redshifts, making possible precise measurements of many aspects of galaxy clustering, which can be studied as a function of galaxy spectral type, and also of broad-band colour. Early-type galaxies are more strongly clustered than late types, with a relative bias of b = 1.25 ± 0.09 on large scales. For both types, luminosity dependence of clustering is detected at high significance, and is well described by a relative bias of b/b* = 0.85 + 0.15(L/L*). This is consistent with the observation that L* in rich clusters is brighter than the global value by 0.28 ± 0.08 mag. Redshift-space distortions from large-scale infall velocities measure the distortion parameter β = Ω0.6m/b = 0.49 ± 0.09. The power spectrum is measured to ≲ 10% accuracy for k > 0.02 h Mpc--1, and is well fitted by a CDM model with Ωmh = 0.18 ± 0.02 and a baryon fraction of 0.17 ± 0.06. The 2dFGRS plays an essential role in breaking model degeneracies inherent in CMB data; a joint analysis with WMAP results requires Ωm = 0.25 ± 15% and h = 0.73 ± 5%, assuming scalar fluctuations.

VLBI observations show that the center of the nearby (~ 3.3 Mpc distant) spiral galaxy, M81, consists of a single elongated radio core, of dimensions 1000 × 4000 AU, with the major axis aligned, in projection, within 3° (<1σ) of the galaxy's rotation axis. This morphology can be interpreted in terms of an active galactic nucleus (AGN) with either a core-jet structure residing in M81's center or an accretion disk filling out the broadline region of this center. In contrast, the radio structure in the companion galaxy, M82, is very complex. VLBI observations of M82 yield the diameters and spectral index distribution of the hot spots, and the morphology and expansion velocity of the brightest hot spot, 41.9+58. Our results argue against the hot spots being core and jet condensations, or young supernovae (SNe), or typical supernova remnants (SNRs). We suggest that the hot spots in M82 are the remnants of stellar events that yielded some combination of SNRs and “exotic” objects.

The present report on the activities of IAU Commission 30, covering the triennium June l, 1984 through June 1, 1987, will be somewhat different from its recent predecessors in both content and style. Over the preceding decade or so, the reports mainly emphasized the dramatic improvements in observing efficiency, achieved primarily through the general adoption of cross-correlation techniques, combined with modern detectors attached to either specialized spectrometers or to existing, more conventional instruments. A great surge of observational activity followed, directed towards a variety of astrophysical problems, some of which are of a more classical nature, but many of which are in entirely new classes of research. At the time of the previous reports, most of the major observational projects were still underway, even if some preliminary results were emerging. The proceedings of IAU Colloquium No. 88, Stellar Radial Velocities (L. Davis Press, 1985) contains a collection of papers on instrumentation and reduction techniques as well as on ongoing observing programs which remains a very useful source of references to this developmental phase as well as to the current state of the art.

During last years, after Budapest Colloquium, flare star investigations have been continued at the Crimean Astrophysical Observatory. The purpose of the investigations was to specify spectral features of flares, to research quantitatively spectra of the stars in quiet state and to search for new variables of this type.

In this paper we review the theories which have been proposed to account for the extra-galactic X-ray background. Although there is still no detailed theory, one may devise reasonable models which account in a natural way both for the intensity and the spectral shape over the whole energy band, provided that cosmological evolutionary effects are included. A model based on Compton scattering of cosmic black body photons by relativistic electrons in radio sources at large redshifts (z ≳ 4) seems to give the most satisfactory explanation. However, the data are not yet good enough to discriminate against alternative models.

A discussion of the recent observations in the soft X-ray region (< 1 keV), and their relevance to the physics of interstellar and intergalactic gas, is given. The available data are somewhat confusing, but it seems that this part of the spectrum may still be consistent with a simple extrapolation of the non-thermal spectrum at higher energies, though various workers have claimed the detection of a new component probably due to hot intergalactic gas. If this interpretation is correct one may deduce interesting conclusions about the state of ionization and composition of the intergalactic gas, because of the importance of the absorption effects in this energy band.

Also it appears that the Galaxy is more transparent than one would deduce from 21-cm observations. However, due to the lack of observational data, no firm conclusions can be reached.

For several of the rapidly oscillating Ap stars the best luminosity estimates available come from the asteroseismological interpretation of their pulsational frequency spectra. We give a list of the 23 currently known roAp stars along with their Strömgren photometric indices, Teff estimated from the Hβ index, and luminosity estimated asteroseismologically. In one case, ϒ Equ, we have an asteroseismological luminosity and a parallax luminosity which are in good agreement. Some of the roAp stars pulsate with frequencies greater than the critical frequency calculated for standard A-star models. This plus multi-colour high-speed photometry of HR 3831 indicate that the temperature gradients in the atmospheres of these stars are substantially steeper than in standard A-star models. We advocate a fine analysis of HR 3831 to see if there is consistency with the pulsational conclusions about T-τ in this star. Further fine analyses and multi-colour pulsational analyses on other roAp stars are then called for. The pulsation mode in HR 3831 can be decomposed into primarily an axisymmetric dipole mode with small radial, quadrupole and octupole perturbations. If the magnetic field is governing the distortion of this mode from a purely dipole mode, then the pulsation can be used to infer the magnetic field geometry. Comments on our current knowledge of all 23 roAp stars are made.

Most of the variable phenomena of high-luminosity (≳1036 erg s−1) stellar X-ray sources can be explained, at least qualitatively, within the general framework of binary accretion models in which thermal X-rays are emitted in the vicinity of a neutron star or blackhole by plasma that has flowed downhill from the surface of a nuclear burning companion and been heated by conversion of its gravitational potential energy. The yield of X-ray energy in this process is so high, exceeding in some cases 0.1c2 per unit mass, that X-ray luminosities in excess of 104L⊙ can be generated with accretion rates of only ˜10−B M⊙ per year. Since the transfer process depends strongly on many parameters that specify the relevant properties of two stars and their interaction, one finds a remarkable variety and range of X-ray phenomena. If the compact object is a magnetized neutron star, rotation will cause its X-ray emission pattern to sweep over a distant observer and thereby produce regular pulsations like those observed with periods in the range from 1 to 103 seconds. Orbital motions can cause regular eclipses and absorption dips like those observed with periods in the range from hours to days. Changes in the rate of mass loss by the nuclear burning star or in the transfer efficiency can account for the variations in intrinsic X-ray luminosities that appear as flares, novae and on-off transitions. Irregularities in the flow of plasma near the compact star can also affect the intrinsic luminosity and appear as erratic fluctuations, spikes and shot-noise in the observed intensity.

I review the progress in research on intracluster planetary nebulae over the last five years. Hundreds more intracluster planetary nebulae have been detected in the nearby Virgo and Fornax galaxy clusters, searches of several galaxy groups have been made, and intracluster planetary candidates have been detected in the distant Coma cluster. The first theoretical studies of intracluster planetaries have also been completed, studying their utility as tracers of the intracluster light as a whole, and also as individual objects.

From the results to date, it appears that intracluster planetaries are common in galaxy clusters (10-20% of the total amount of starlight), but thus far, none have been detected in galaxy groups, a result which currently is not well understood. Limited spectroscopic follow-up of intracluster planetaries in Virgo indicate that they have a complex velocity structure, in agreement with numerical models of intracluster light. Hydrodynamic simulations of individual intracluster planetaries predict that their morphology is significantly altered by their intracluster environment, but their emission-line properties appear to be unaffected.

In 2014, a 179-orbit allocation of Hubble Space Telescope time anchored a massive reverberation-mapping program on the well-studied Seyfert 1 galaxy NGC 5548. Supporting imaging and spectrophotometric observations were provided by Swift, Chandra, Spitzer, and a world-wide network of ground-based telescopes. Understanding the data remains a significant challenge, partly because the level of detail is far beyond what has been seen before and partly because the behavior of the AGN was not typical of its past behavior. Based on analysis to date, the following conclusions can be reached: (1) the AGN accretion disk has a temperature profile that is consistent with that predicted by the Shakura–Sunyaev model, but is about three times larger than expected; (2) at least part of the broad-line region appears to be a Keplerian disk seen at intermediate inclination, and (3) the broad-line emission response from the far side of the disk is weaker than expected.