The most resonant pulsation frequency of δ Scuti stars     

S. V. Kotov  V. A. Kotov 《Astronomische Nachrichten》1997,318(2):121-128

Pulsation of the Sun with a period of P₀ ≈ 160 min discovered about two decades ago, is still waiting explanation. In view of the hypothesis about its cosmological origin, and attempting to find signature of this P₀ periodicity among other (short-period variable) stars, the pulsation frequencies of δ Sct stars are subjected to specific analysis. With a confidence level ≈ 3.8σ it is found that the frequency v₀ = P₀⁻¹ ≈ 104 m̈Hz, within the error limits, appears indeed to be the most “resonant” one for the total sample of 318 pulsating stars of δ Sct type (the most commensurable, or “synchronizing”, period for all these stars occurs to be 162 ± 4 min). We conjecture that a) the P₀ oscillation might be connected with periodic fluctuations of gravity field (metrics), and b) the primary excitation mechanism of pulsations of δ Sct stars, reffected by this “ubiquitous” P₀ resonance, must be attributed perhaps to superfast rotation of their inner cores (their rates tend to be in near-resonance with the “universal” v₀ frequency). The arguments are given favouring a cosmoogical nature of the P₀ oscillation.  相似文献   

Ejection of positrons from the surface of pulsars by ultrarelativistic electrons     

S. V. Bogovalov  Yu. D. Kotov 《Astrophysics》1989,31(1):490-498

Moscow Engineering Physics Institute. Translated from Astrofizika, Vol. 31, No. 1, pp. 124–136, July–August, 1989.  相似文献   

The Paleozoic age of high-pressure metamorphic rocks in the Dakhov Salient, northwestern Caucasus: Results of U-Pb geochronological investigations     

M. L. Somin  O. A. Levchenkov  A. B. Kotov  A. F. Makeev  A. N. Komarov  N. I. Ro  V. A. Lavrishchev  V. A. Lebedev 《Doklady Earth Sciences》2007,416(7):1018-1021

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The Toksko-Algomin igneous complex of the Dzhugdzhur-Stanovoi folded region: Age and geodynamic setting     

E. B. Sal’nikova  A. M. Larin  A. B. Kotov  A. P. Sorokin  A. A. Sorokin  S. D. Velikoslavinsky  S. Z. Yakovleva  A. M. Fedoseenko  Yu. V. Plotkina 《Doklady Earth Sciences》2006,409(2):888-892

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Sm-Nd isotopic provinces of the Aldan Shield     

A. B. Kotov  E. B. Sal’nikova  V. A. Glebovitsky  V. P. Kovach  A. M. Larin  S. D. Velikoslavinsky  N. Yu. Zagornaya 《Doklady Earth Sciences》2006,410(1):1066-1069

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Sources and provenances of lower proterozoic terrigenous rocks of the Udokan group, Southern Kodar-Udokan depression: Results of Sm-Nd isotopic investigations     

V. N. Podkovyrov  A. B. Kotov  A. M. Larin  L. N. Kotova  V. P. Kovach  N. Yu. Zagornaya 《Doklady Earth Sciences》2006,408(1):518-522

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Early Proterozoic age of the Tyrkandin fault zone, the Aldan Shield: U-Pb dating of fragments of single zircon grains     

E. B. Sal’nikova  A. B. Kotov  V. I. Kazansky  V. A. Glebovitsky  N. N. Pertsev  S. Z. Yakovleva  A. M. Fedoseenko  Yu. V. Plotkina 《Doklady Earth Sciences》2006,408(1):538-541

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Coordinated monitoring of the eccentric O-star binary Iota Orionis: optical spectroscopy and photometry     

Sergey V. Marchenko  Gregor Rauw  Eleonora A. Antokhina  Igor I. Antokhin  Dominique Ballereau  Jacques Chauville  Michael F. Corcoran  Rafael Costero  Juan Echevarria  Thomas Eversberg  Ken G. Gayley  Gloria Koenigsberger  Anatoly S. Miroshnichenko  Anthony F. J. Moffat  Nidia I. Morrell  Nancy D. Morrison  Christopher L. Mulliss  Julian M. Pittard  Ian R. Stevens  Jean-Marie Vreux  Jean Zorec 《Monthly notices of the Royal Astronomical Society》2000,317(2):333-342

With the objective of investigating the windwind collision phenomenon and supporting contemporaneous X-ray observations, we have organized a large-scale, coordinated optical monitoring campaign of the massive, highly eccentric O9 III+B1 III binary Iota Orionis. Successfully separating the spectra of the components, we refine the orbital elements and confirm the rapid apsidal motion in the system. We also see strong interaction between the components during periastron passage and detect phase-locked variability in the spectrum of the secondary star. However, we find no unambiguous signs of the bow shock crashing on the surface of the secondary, despite the predictions of hydrodynamic simulations. Combining all available photometric data, we find rapid, phase-locked variations and model them numerically, thus restricting the orbital inclination to 50° i 70°.  相似文献   

TEM study of the geoelectrical structure and groundwater salinity of the Nahal Hever sinkhole site, Dead Sea shore, Israel   总被引：1，自引：0，他引：1  

Michael Ezersky  Anatoly Legchenko  Abdallah Al-Zoubi  Eldad Levi 《Journal of Applied Geophysics》2011,75(1):99-112

Since the 1990s a large number of sinkholes have appeared in the Dead Sea (DS) coastal area. Sinkhole development was triggered by the lowering of the DS level. In the literature the relationship between the sinkholes and the DS level is explained by intrusion of relatively fresh water into the aquifer thereby dramatically accelerating the salt dissolution with creation of subsurface caverns, which in turn cause sinkholes. The main goal of our project was detection and localization of relatively fresh groundwater. During our study we used the transient electromagnetic method (TEM) to measure the electrical resistivity of the subsurface. As a test site we selected Nahal Hever South which is typical for the DS coast. Our results show that resistivity of the shallow subsurface reflects its vertical and lateral structure, e.g., its main hydrogeological elements explain the inter-relations between geology, hydrogeology, and sinkholes. The TEM method has allowed detailed differentiation of layers (clay, salt, etc.) in the subsurface based on their bulk resistivity. The 10 m-thick salt layer composed of idiomorphic crystals of halite deposited during the earlier Holocene period was extrapolated from borehole HS-2 through the study area. It was found that in Nahal Hever the typical value of the bulk resistivity of clay saturated with the DS brine varies between 0.2 and 0.3 Ωm, whereas saturated gravel and sandy sediments are characterized by resistivity between 0.4 and 0.6 Ωm. The high water salinity of the aquifer (enveloping the salt layer) expressed in terms of resistivity is also an important characterization of the sinkhole development mechanism. The electrical resistivity of the aquifer in the vicinity of the salt unit and its western border did not exceed 1 Ωm (in most cases aquifer resistivity was 0.2-0.6 Ωm) proving that, in accordance with existing criteria, the pores of the alluvial sediments are filled with highly mineralized DS brine. However, we suggest that the criterion of the aquifer resistivity responsible for the salt dissolution should be decreased from 1 Ωm to 0.6 Ωm corresponding to the chloride concentration of approximately 100 g/l (the chloride saturation condition reaches 224 g/l in the northern DS basin and 280 g/l in the southern one).Based on TEM results we can reliably conclude that in 2005, when most of sinkholes had appeared at the surface, salt was located within a very low resistivity environment inside sediments saturated with DS brine. Intrusion of relatively fresh groundwater into the aquifer through the 600 × 600 m²area affected by sinkholes has not been observed.  相似文献   

Isotopic structure and evolution of the continental crust in the East Transbaikalian segment of the Central Asian Foldbelt     

E. Yu. Rytsk  V. P. Kovach  V. V. Yarmolyuk  V. I. Kovalenko  E. S. Bogomolov  A. B. Kotov 《Geotectonics》2011,45(5):349-377

New data on the geology and tectonics of the main structural elements of the East Transbaikalian segment of the Central Asian Foldbelt are discussed. Correlation charts of the main stratified and igneous complexes are compiled. The rocks of the Baikal-Patom and Baikal-Muya belts, as well as the Barguzin-Vitim Superterrane, are characterized by new Nd isotopic data, which have allowed us to establish the sources of these rocks, to separate isotopic provinces, and to distinguish two stages of crust-forming processes: the Early Baikalian (1.0–0.8 Ga) and the Late Baikalian (0.70–0.62 Ga). The Early Baikalian crust was formed in relatively narrow and spatially isolated troughs of the Baikal-Muya Belt and probably in the Amalat Terrane, whereas the Late Baikalian continental crust was formed and reworked in the Karalon-Mamakan, Yana, and Katera-Uakit zones of the Baikal-Muya Belt. The Baikal-Patom Belt and most of the Anamakit-Muya Zone in the Baikal-Muya Belt are characterized by remobilization of the Early Precambrian continental crust and by a subordinate role of Late Riphean juvenile sources. Reworking of the mixed Late Riphean and Early Precambrian crustal sources is typical of the Barguzin-Vitim Superterrane. The origination and evolution of the continental crust in the studied region are considered in light of new data; alternative versions of paleogedynamic reconstructions are discussed.  相似文献