No abstract available

[en] Our multi-epoch survey of ∼20 deg² of the Canis Major (CMa) overdensity has detected only 10 RR Lyrae stars (RRLS). We show that this number is consistent with the number expected from the Galactic halo and thick disk populations alone, leaving no excess that can be attributed to the dwarf spheroidal (dSph) galaxy that some authors have proposed as the origin of the CMa overdensity. If this galaxy resembles the dSph satellites of the Milky Way (MW) and of M31 and has the putative M_V ∼ -14.5, our survey should have detected several tens of RRLS. Even if M_V ∼< -12, the expected excess is ∼>10, which is not observed. Either the old stellar population of this galaxy has unique properties or, as others have argued before, the CMa overdensity is produced by the thin and thick disk and spiral arm populations of the MW and not by a collision with a dSph satellite galaxy.

[en] The formula to estimate the possibility of existence of planetary system in a star taking into account the multiplicity of star systems, is suggested. It is shown that the possibility of formation of planetary system can be estimated by Psub(ps) approximately 0.23 value. This gives the estimate of the general number of planetary systems in the Galaxy (where approximately 2x10¹¹ stars) - approximately 4.6x10¹⁰. In the radius of 10 ps 120-140 planetary systems can be expected

[en] The first international conference on the central region of our galaxy was held at UCLA during July 25-29, 1988. Radio, infrared, X-, and γ-ray astronomers, benefitting from recent technological advances, confronted theorists, as well as each other, with impressive new imagery in each of these domains. Traditionally hidden by an impenetrable veil of dust, the galactic center is now largely transpasrent, particularly in the near-IR, where the extinction toward the galactic center is an order of magnitude less than at optical wavelengths. On the large scale, one observes a large reservoir of molecular gas, some of which is exhibiting complex, noncircular motions. Some of the kinematical behavior is best explained in terms of energetic explosions occurring about 10⁷ years ago. The radio continuum reveals numerous filaments of ionized gas, and strong, poloidal magnetic fields are implied, quite unlike the field anywhere else in the galaxy. On small scales, much effort is going into the attempt to identify a unique objedct at the nucleus that may or may not be a massive black hole (a mass of 3x10⁶ M_sun has been defended). Candidates exist for a compact mass concentration, and for a strong central luminosity source, but they are not necessarily one and the same, and there are problems identifying any of the candidates with a massive accreting object at the center. Surrounding the dynamical center of the galaxy is the prominent radio source Sgr A, which includes a warm, turbulent circumnuclear disk on 5 to 10 pc scales, streamers of ionized gas which may represent flows of material into the central potential well, and a background shell of nonthermal radio emission, probably a superimposed supernova remnant. This summary describes some of the current research activity on the galactic center, with particular attention to the implications of X- and γ-ray observations. (orig.)

[en] The Milky Way harbors giant H II regions, which may be powered by star complexes more luminous than any known Galactic OB association. Being across the disk of the Galaxy, however, these brightest associations are severely extinguished and confused. We present a search for one such association toward the most luminous H II region in the recent catalog by Murray and Rahman, which, at ∼9.7 kpc, has a recombination rate of ∼7 x 10⁵¹ s^-1. Prior searches have identified only small-scale clustering around the rim of this shell-like region, but the primary association has not previously been identified. We apply a near-infrared color selection and find an overdensity of point sources toward its southern central part. The colors and magnitudes of these excess sources are consistent with O- and early B-type stars at extinctions 0.96 < A_K < 1.2, and they are sufficiently numerous (406 ± 102 after subtraction of field sources) to ionize the surrounding H II region, making this a candidate for the most luminous OB association in the Galaxy. We reject an alternate theory, in which the apparent excess is caused by localized extinction, as inconsistent with source demographics.

No abstract available

[en] At visual inspection of objective-prism plates of Milky Way regions one frequently detects pairs or sometimes higher multiples of spectra which are so similar in appearance and so close together that they form a conspicuous configuration for the eye. A statistical analysis shows that the observed occurrence of this phenomenon, down to a certain limiting magnitude and up to a certain value of the angular separation of the components, considerably exceeds the expected one - if it should be considered as produced entirely by random coincidence. Therefore it is reasonable to assume a physical explanation behind this sort of agglomeration. In connection with a large survey of the Southern Milky Way, carried out at the Stockholm and Uppsala observatories, several thousands of such coincidences have been registered. About a hundred of them have been subjected to a special investigation, intended to give an answer to the question about their physical interpretation. Although the methods have been neither very rational, nor always point-to-point reliable, the scrutiny has shown pretty well that an overwhelming majority of the 'candidate' objects do reveal stellar clusterings of various types. (Auth.)

No abstract available

[en] The results of comparison of the Abastumani Catalogue of Trapezium Type Multiple Systems with known catalogues of associations, galactic clusters and emission nebulae are presented. Belonging to a large number of Trapezium systems of the O-B2 spectral classes to the latter is established. In many cases the Trapezia at the same time are members of associations, galactic clusters and emission nebulae. The results obtained confirm the Ambartsumian conclusion on Trapezium type stellar systems to be young

[en] A qualitative model for the galactic field of force is postulated together with a classification of the different zones of the Galaxy according to their observed ranges in velocity dispersions and the behaviour of the potential well at different z-altitudes. The disk containing at least two-thirds of the total mass at z <= 600-800 pc, and the halo at higher z-altitudes with a small fraction of such a mass which is difficult to evaluate. (orig./WL)