We have carried out a search for obscured AGB stars in the LMC, observing fields in the vicinity of faint IRAS sources. About 25 heavily reddened AGB stars were found, with bolometric magnitudes close to the classical AGB limit of Mbol = −7.1. 10−µm. photometry for 5 sources show that these are oxygen-rich; they are similar to the Galactic OH/IR stars. Mass-loss rates vary between 5×10−4 and 2×10−6 M⊙ yr−1. We find no evidence that the mass-loss rates vary with luminosity. Neither do the mass-loss rates differ in a clear systematic way between the SMC and the LMC. The expansion velocities appear to be slightly lower in the LMC than in the Galaxy. All of the luminous stars for which periods are available have luminosities significantly above the period-luminosity relation derived for optical LMC Miras.

The present report gives the results on the Hα line profile investigation of two the most well-known A0e Herbig stars of the so-called P Cyg -subgroup: AB Aur and HD 163296. 35 high-resolution CCD spectra (R ~ 50 000) of HD 163296 (ESO, CAT+CES, July 1991 and 1992) and 43 CCD spectra (R ~ 30 000) of AB Aur (Crimean Observatory, 2.6-meter telescope, January 1993) were obtained. A striking profile variability is discovered in both objects on the timescale from one our to a few days. The most dominant part of rapid variations (τ ~ hours) is the monotonous flux drift of different profile components. Positional shift of sharp spectral bumps, found in HD 163296 is probably connected with local inhomogeneities moving in the envelope. Shape variability of the absorption P Cyg -component of the Hα -line in AB Aur is suspected to be periodic with P = 35 or 70 hours. A model for a circumstellar envelope is proposed to explain the observed variability in this type of objects. It supposes the existence of an active non-stable region near the star, formed by equatorially concentrated stellar wind and an outer cool shell.

We discuss the “rotation” curves of SB0 galaxies with self-consistent models constructed with Schwarzschild’s method. Their distribution functions are compared with that of N-body simulations.

A new research for the secular drift of the Earth's pole was made based on nine long sequences of latitude observations and led to the following conclusions.

1. 1. During this century, the Earth's pole has been moving with a mean rate of about 0″.0016/yr along the meridian about 70° (W). This drift rate is much less than the 0″.0035/yr derived from the ILS sequence.

2. 2. Relative to the North American continent, the Ukiah station located on the west coast of the U.S. shows a local drift of about 6 cm/yr northward, which coincides well with that determined by new techniques.

3. 3. Referring to the Europe-Asia plate, the whole North American continent shows a drift northward with a rate of about 8 cm/yr. The Mediterranian shows a similar drift of about 6 cm/yr. Perhaps these drifts are the consequences of plate motion and/or deflection of local vertical. It is useful for ascertaining the sources of the drifts to intercompare longer sequences observed with different techniques, including classical and new ones.

4. 4. Three of five ILS stations, Ukiah, Gaithersburg, and Carloforte, show significant local drifts. Therefore, the Conventional International Origin (CIO), which is defined by the 1903.0 mean latitudes of five ILS stations, is far from fixed on the Earth's surface. It is necessary to re-define an origin of the pole of the Conventional Terrestrial System (CTS).

5. 5. The quasi-30-year libration showed by the ILS data is not the real pattern of the Earth's polar motion, but results from both the irregular polar motion over some period and the local motion of Ukiah.

Short period terms ranging from 0.3 to 6.0 yr. are resolved from 13.5 yr data of UT1 and polar motion on periodograms, considering the mutual interference effects caused by truncation of data. Beside principal terms known well, 26 month term is reconfirmed but any Chandlerian term is not found in UT1. Minor amplitude terms are found around 0.48, 0.86, 1.36, 1.58, 3, and 4 yr in UT1, and 1.12, 1.26, and 1.43 yr in polar motion.

We compare the relative merits of four different types of instrument for tridimensional spectrometry at visible and ultraviolet wavelengths: the echelle and long-slit spectrographs and two types of Fourier transform spectrometer (conventional scanning and fixed tilt spatially heterodyned). Each of these instruments requires different spatial and spectral scanning modes. It is shown that in certain limiting conditions all four are equally efficient, but that they differ in other important characteristics.

We have obtained optical recombination-line abundances for the third-row element magnesium in ten planetary nebulae. The nebulae in our sample include four (NGC 7009, NGC 6153, M 2–36 and M 1–42) for which we have previously found very large enhancements, relative to solar, in the recombination line abundances of the second-row elements carbon, nitrogen, oxygen and neon (Liu et al. 1995, Liu et al. 2000, Liu et al. 2001). Nebular temperature fluctuations appear unable to account for these effects. However, models that invoke high-density clumps, particularly clumps which are hydrogen-deficient, appear more viable as an explanation for the high recombination line abundances that are observed (see Liu et al. 2000 for more details). While it may be possible to appeal to astrophysical nucleosynthetic processes to enhance the CNONe second-row elements in AGB stars, such effects are not expected to modify the abundances of third-row elements such as magnesium. We have therefore measured and dereddened the intensities of the 4481 Å 4f-3d line of Mg II, relative to Hβ, in order to investigate whether magnesium recombination line abundances are enhanced or not.

The extent and nature of molecular material in the outer Galaxy (R > R⊙) has been an open, interesting question since the discovery of molecular material in the outer Galaxy (Kutner & Mead, 1981). From large scale CO surveys, two estimates of the total molecular mass have been made with the same result, M(H2) = 6 × 108 M⊙ (Wouterloot et al., 1990), (Digel et al., 1990). Both estimates have a strong bias towards large, star forming (warm) clouds. Wouterloot et al. used the IRAS point source catalog as a finder chart for their observations and the inner Galaxy mass distribution to scale their result. Digel et al. conducted an unbiased survey with a large (8.8 arcminute) beam which underestimated the amount of material in small clouds due to the effects of beam dilution.

We have completed a direct narrow-band/broad-band Schmidt-plate survey of large areas of the southern Milky Way for new Wolf-Rayet stars as faint as 19th b magnitude. The 31 newly detected stars in the completed survey are amongst the reddest and/or most distant known in the Galaxy. We have obtained spectra of all candidate WR stars in the 22 fields stretching from l = 282° to l = 341° in longitude, and Δb = 3.5° in latitude, covering about 180 square degrees. We also observed two isolated Milky Way fields centered at l = 0° and l = 8°. Eighteen new WR stars are reported here for the first time. Combined with the 13 new WR stars we have already reported in Carina, our list of 31 new Galactic WR stars reaches 3–4 magnitudes fainter than previous surveys. Thirteen of the 18 new WR stars reported here are of subtype WN, while five are of subtype WC. Our new WR stars clearly demonstrate an increasing WN/WC number ratio with increasing Galactocentric distance.

At the Institute for Theoretical Astronomy we have formed a library containing about 120 standard computer programmes. They include calculation of rectangular coordinates and velocities from elements, Lagrangian interpolation, and orbit improvement by the Eckert-Brouwer method. For the investigation of the motions of the minor bodies of the solar system we have constructed a programme for integration with a variable step and making allowance for perturbations by all the major planets and for nongravitational effects. The calculation of the perturbations is carried out using Herrick's vector parameters by the method of variation of arbitrary constants. The programme has been used for studying the motion of P/Encke.

The relations between the physical parameters of the RRab stars and the Fourier parameters of their light curves have been reanalyzed on the basis of new CCD data. We show that the absolute magnitude MV and the dereddened color indices (B − V)0, (V − I)0 are linear functions of the period and of the A1 Fourier amplitude of the V light curve. Due to the large datasets, we are able to test the consistency of the formulae on independent sets. The present results are in good or fair agreement with our previous studies, despite the fewer number of significant parameters entering in the revised formulae.

Although the subject of this meeting is triggered star formation in a turbulent interstellar medium, it remains unsettled what role magnetic fields play in the star formation process. This paper briefly reviews star formation model predictions for the ratio of mass to magnetic flux, describes how Zeeman observations can test these predictions, describes new results – an extensive OH Zeeman survey of dark cloud cores with the Arecibo telescope, and discusses the implications. Conclusions are that the new data support and extend the conclusions based on the older observational results – that observational data on magnetic fields in molecular clouds are consistent with the strong magnetic field model of star formation. In addition, the observational data on magnetic field strengths in the interstellar medium strongly suggest that molecular clouds must form primarily by accumulation of matter along field lines. Finally, a future observational project is described that could definitively test the ambipolar diffusion model for the formation of cores and hence of stars.

It was recommended in a resolution of the International Astronomical Union that as of Jan. 1, 1984, a new astronomical reference frame would be adopted (IAU 1976). This reference frame has been designated as the FK5 reference frame of J2000.0. The problem of the interim realization of this reference frame pending completion of work on the compilation of the FK5 catalog at the Astronomisches Rechen-institut has been addressed by a number of authors, see, e.g., Kaplan(1981), Standish(1983), Aoki et al.(1983), and Lederle and Schwan(1984). Their discussions are primarily concerned with the steps which must be taken to transform FK4 catalog positions and proper motions referred to the equator, equinox and epoch of B1950.0 to J2000.0. The primary emphasis of the following discussion is on the transformation of catalogs other than the FK4 to the J2000.0 equinox. There are a few remarks concerning the FK4 catalog.

The distances are determined for 142 Galactic planetary nebulae, using two methods. Method A is based on the stellar mass and surface gravity, while Method B makes use of the stellar luminosity. These properties of the central star are inferred from the modeling of the distance-independent parameters (Zhang and Kwok 1992). The results from the two methods used in this paper are consistent with each other. A distance of 10.8 kpc is found for K648 using Method A of this work. This is in excellent agreement with the distance of 10 kpc of its hosting globular cluster M15. The distances obtained in this work are in good agreement with the distances of Mendez et al. (1992), based on the recently developed non-LTE model atmospheres including spherical extension and stellar winds. The agreement of our distances with the individually determined distances of Gathier et al. (1986a, 1986b), using the extinction-distance method and the HI 21 cm absorption method, is worse than that found between ours and Mendez et al.'s. The distances obtained by Gathier et al. are likely often to be underestimated. The various statistical distance scales, except for Cudworth's (1974) distance scale, show no agreement with the distances determined in this work. CYZ was supported by the NASA grant NAG 2–67.

The properties of the different types of QSO absorption systems are briefly summarized. An overview is given of the potential applications of absorption lines in cosmology. Recent work on the cosmological evolution of the different types of absorbers is discussed. The physical properties of the intergalactic medium are discussed in the light of recent work on the “Lyman alpha clouds”. The uses of the lines for studies of the evolution of clustering in the Universe are described. Recent puzzling results on common absorption in pairs of QSOs, particularly Q1037–2704 and Q1038–2712, are summarized.

This conference is concerned with the very high resolution imaging of cosmic sources in many parts of the electromagnetic spectrum. Various techniques are now available and the equipment is often automated and highly sophisticated but the term ‘very high angular resolution’ is comparative. Many of the problems existed over forty years ago when the best resolving power was about half a degree and the two major radio ‘stars’ appeared to be point sources. Very high resolution imaging in those days was the struggle to reach one minute of arc and Hanbury Brown had set his sights on considerably better than one second of arc with the concept of the intensity interferometer. The dream was to achieve a resolving power comparable to that of optical telescopes.

We present results of thermal and vibrational stability analysis for 1 M⊙ white dwarf models corresponding to various accretion rates ≳ 10−11 M⊙/y. Accretion is assumed to be spherically symmetric and stationary. Thermal instability due to nuclear burning of hydrogen (at lower accretion rates) and helium (at higher rates) was found. At medium rates two growing thermal modes are simultaneously present. Vibrational instability was found for all models except those corresponding to highest accretion rates. The excitation rates for some nonradial g-modes are at least 3 orders of magnitude higher than those for radial pulsations. These rates are also higher than the excitation rates for thermal modes in certain range of accretion rates corresponding to high luminosities and effective temperatures. Among objects in which these instabilities may be important are symbiotic stars and nuclei of planetary nebulae.

The radio continuum emission of the Milky Way and nearby galaxies can be decomposed into a central region, a clumpy “thin disk”, concentrated in the spiral arms, and a smooth “thick disk” (or flattened “halo”). The emissivity ratio of the two disks seems to be related to the magnetic field properties: Galaxies with strong radio spiral arms reveal a highly ordered field following the arm direction, while galaxies with diffuse disks contain a less ordered, smoothly distributed field. The degree of uniformity of the field seems to correlate with the total optical luminosity. The average magnetic field in the Milky Way is weak and turbulent compared to most of the nearby galaxies observed so far.

The distribution of matter condensing out of cooling flows in clusters of galaxies and individual elliptical galaxies has been studied using X-ray data and is found to resemble the expected mass profiles of the underlying galaxies. Most of the cooled gas must create objects of high mass-to-light ratio, although some more normal stars are produced. Cooling flows provide an observable mechanism for the continual formation of dark matter around galaxies. Since the conditions at galaxy formation are similar to those in cooling flows if the gas reaches the virial temperature, we suggest that they are local models of galaxy formation.