The structure of the tectonosphere of the Urals and West Siberian Platform by electromagnetic data     

A. G. D’yakonova  K. S. Ivanov  O. V. Surina  P. F. Astaf’ev  V. S. Vishnev  A. D. Konoplin 《Doklady Earth Sciences》2008,423(2):1479-1482

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The Sunyaev-Zel’dovich effect in elliptical galaxies     

B. V. Komberg  D. I. Nagirner  I. V. Zhuravleva 《Astronomy Reports》2008,52(9):707-713

The history of the discovery of hot gas in galaxies is briefly reviewed, and the main properties of this gas described, emphasizing the need to refine these properties, in particular, the mass of the gas. It is proposed to do this via observations of the Sunyaev-Zel’dovich (SZ) effect due to hot gas in the coronas of elliptical galaxies. The absolute and relative perturbations of the spectrum of the cosmic microwave background (CMB) radiation due to scattering of the CMB photons by electrons with a Maxwellian energy distribution are calculated. The possibility of observing the SZ effect is demonstrated using three elliptical galaxies as examples. The kinematic SZ effect arising due to the peculiar motions and rotations of the galaxies is also accessible to observations. Together with X-ray data, such observations would enable refinement of the properties of gas in galaxies, and also yield additional information about the rotation of galaxies, possible accretion flows in the galactic gas, and hot galactic winds.  相似文献   

Different magneto-rotational supernovae     

G. S. Bisnovatyi-Kogan  S. G. Moiseenko  N. V. Ardelyan 《Astronomy Reports》2008,52(12):997-1008

We present the results of two-dimensional calculations of a magneto-rotational (MR) supernova explosion with a collapsing core for various core masses, rotational angular momenta, and magnetic-field configurations. It is shown that the MR mechanism produces an explosion energy that corresponds to observed values. The form of the explosion depends substantially on the initial configuration of the magnetic field. MR instability develops during the evolution of the magnetic field in an MR supernova explosion, resulting in an exponential increase of all components of the magnetic field, thereby substantially decreasing the time scale of the MR explosion. The energy of the supernova increases with the core’s mass and initial rotational energy.  相似文献   

Fluid inclusion and stable isotope characteristics of the Karalar (Gazipaşa,Antalya) barite-galena deposits,Southern Turkey     

A. Gökşe  G. Bozkaya 《Geology of Ore Deposits》2008,50(2):145-154

The Karalar galena-barite deposits are typical examples of the carbonate-hosted barite-galena deposits widely occurring in the Central Tauride Belt. These deposits are located in Permian limestones as ore veins along fault zones that are discordant to the bedding planes and as thin veinlets within hardly brecciated bottom zones of Permian limestones. The ore deposits contain mainly barite and galena and small amounts of sphalerite, pyrite, fahlore, limonite, quartz, and calcite. Barites occur during the earlier episode of mineralization and were mylonitized before the formation of galena. Galena and other minerals occur epigenetically with barite along porous zones between brecciated barite crystals and are especially abundant in the hardly mylonitized zones. Fluid inclusion studies indicate that the ore deposits of the area were developed by hydrothermal fluids with following characteristics: they contained NaCl, CaCl₂, and MgCl₂; the salinity of the fluids was relatively high and their temperature was low during the crystallization of barites in the earlier episode of mineralization; and the salinity of the fluids decreased and their temperature increased during the crystallization of sulfide minerals through the later episode of mineralization. δ₁₈O and the δD results indicate that the water in the mineralizing fluid was of meteoric origin. The deposits were formed by deep meteoric water circulating through marine sediments. Shallow circulating and slightly warmed fluids dissolved Ba and sulfate from marine sediments of the basement and transported them to the mineralization environment during the early episode, while deep circulating and more heated fluids dissolved Pb, Zn, and other elements from the basement and reached the environment during the later episode of mineralization. The text was submitted by the authors in English.  相似文献   

Normative quartz as an indicator of the mass transfer intensity during the postmagmatic alteration of the Botuobinskaya pipe kimberlites (Yakutia)     

V.B. Vasilenko  A.V. Tolstov  V.A. Minin  L.G. Kuznetsova  N.V. Surkov 《Russian Geology and Geophysics》2008,49(12):894-907

The intensity of postmagmatic processes in the Botuobinskaya pipe kimberlites was estimated from the calculated content of normative secondary quartz (Q). Several simple algorithms are proposed to calculate the Q content from chemical analyses of kimberlites. Ten groups of altered kimberlites have been recognized from the Q contents. The contents of MgO, some trace elements, and LREE in the groups, the contents of Cr and Ca of crimson garnets, the diamond contents of kimberlites, and the average weight of diamonds decrease as the Q content increases. It is shown that the negative SiO₂–MgO correlation is the most effective indicator of the postmagmatic alteration of kimberlites. As the degree of their secondary alteration increases, the kimberlites transform into an assemblage of quartz and clay minerals enriched in some trace elements and almost completely lacking REE and diamonds.  相似文献   

Melt inclusions in eclogite garnet: experimental study of natural processes     

A.L. Perchuk  V.O. Yapaskurt  V.V. Davydova 《Russian Geology and Geophysics》2008,49(5):310-312

Experiment with poikilitic garnet at 3 GPa and 800 °C showed dehydration melting of its mineral inclusions, which is accompanied by the growth of (sub)euhedral garnet crystals inside the inclusion and/or xenomorphic garnets replacing the host mineral. The newly formed and host garnets differ drastically in composition. The inclusion surface is complicated by specific wedge-like protrusions or thin branches composed of melt or its crystallization products. The above features have been discovered in polymineral inclusions in garnet from low-temperature (650 °C) eclogite from the Yukon-Tanana terrane, Canada. The inclusions are interpreted as the crystallization products of in situ formed melt.  相似文献   

Climatic changes and alluvial-sedimentation settings in southeastern Transbaikalia in the Middle-Late Holocene (by the example of the Ilya floodplain)     

V.B. Bazarova  L.M. Mokhova  M.A. Klimin  L.A. Orlova  K.Yu. Bazarov 《Russian Geology and Geophysics》2008,49(12):978-985

Climatic changes in southeastern Transbaikalia in the Middle and Late Holocene and their influence on alluvial sedimentation environments are reconstructed from the results of study of the Ilya floodplain sediments (Alkhanai National Park). At the beginning of the Subboreal period, the regional climate became more arid, which led to a significant increase in steppe species communities in the landscapes. Intense climate aridization also took place at the beginning and at the end of the Subatlantic period of the Holocene. The alluvial-sedimentation rate increased during the weakening of aridization and decreased during cooling and the intensification of aridization. The obtained regional data are compared with data on the adjacent areas and the global climatic changes in the Northern Hemisphere.  相似文献   

Intrayear irregularities of the Earth’s rotation     

L. D. Akulenko  Yu. G. Markov  V. V. Perepelkin  L. V. Rykhlova 《Astronomy Reports》2008,52(7):590-597

The methods of celestial mechanics can be used to construct a mathematical model for the perturbed rotational motions of the deformable Earth that can adequately describe the astrometric measurements of the International Earth Rotation Service (IERS). This model describes the gravitational and tidal influences of the Sun and Moon. Fine resonant interactions of long-period zonal tides (annual, semiannual, monthly, and biweekly) with the diurnal and semidiurnal tides are revealed. These interactions can be reliably confirmed via a spectral analysis of the IERS data. Numerical modeling of tidal irregularities of the Earth’s axial rotation was carried out, focusing on the analysis and forecasting of variations of the day length occurring within short time intervals of a year or shorter (intrayear variations).  相似文献   

Population synthesis for massive close WR20a-type binaries     

A. I. Bogomazov  A. M. Cherepashchuk 《Astronomy Reports》2008,52(12):1009-1014

We have used the “Scenario Machine” to carry out a population synthesis for close binary systems with the masses of both components and their orbital periods similar to those for the WR20a system. The possible qualitative composition of WR20a, the most massive known binary with non-degenerate components (commonly classified as Wolf-Rayet stars according to their observational parameters), has been studied. Meridional circulation may enrich the envelope of a rapidly rotating main-sequence star in CNO elements. In the most likely model, WR20a consists of a Wolf-Rayet star and a main-sequence star.  相似文献   

The gas density and “volume” Schmidt law for spiral galaxies     

O. V. Abramova  A. V. Zasov 《Astronomy Reports》2008,52(4):257-269

The equilibrium thickness of the isothermal layers of interstellar gas and volume gas densities ρ _gas in the plane of the disk as a function of galactocentric distance R are computed for seven spiral galaxies (including the Milky Way) using an axisymmetrical model. In this model, the thickness of the stellar disk varies with R and remains approximately equal to the minimum thickness of a stable equilibrium disk. We found the disk thickness to increase toward the periphery in at least five of the seven galaxies. The density of the stellar disk decreases with R faster than ρ _gas , so that gas dominates at the disk peripheries in terms of density. A comparison of the azimuthally averaged star formation rate SFR and the gas density shows the absence of a universal Schmidt law SFR ～ρ _gas ⁿ for galaxies. However, the SFRs in various galaxies are better correlated with the volume than the gas surface density. The parameter n in the Schmidt law formally calculated using the least-squares method lies in the interval 0.8–2.4, being, on average, close to 1.5. The values of n calculated separately for the molecular gas display substantial scatter, but are, on average, close to unity. The value of n appears to increase with decreasing ρ _gas , so that the fraction of gas that actively participates in star formation decreases with n.  相似文献