The formation age of ores from the Pebble Cu-Au-Mo giant deposit (Alaska,United States)     

A. A. Kremenetskii  V. S. Popov  N. A. Gromalova 《Doklady Earth Sciences》2012,442(2):196-201

Zircons from the porphyry-like quartz-diorite boss of the Pebble Cu-Au-Mo deposit (southwest Alaska) have been examined. By their appearance and internal structure (cathode luminescence and electron probing), the zircons have been subdivided into four genetic groups: (1) xenogenic detrital (mainly rounded); (2) magmatogene (protolith crystal in the center and growth zone at the edge); (3) hydrothermally altered (with new-formed regeneration edges in growth zones); (4) metamict-altered (unconsolidated center of the crystal and sectoring in growth zones). Based on SHRIMP U-Pb dating for the principal heterogeneous elements in every group, the following stages of ore formation have been identified for the Pebble deposit: (a) crystallization of quartz diorite-porphyry bosses (95–92 Ma, the concordant age is 94.7 ± 1.5 Ma); (b) late magmatic metasomatic alterations with copper-molybdenum mineralization (92–85 Ma, the concordant age is 90.15 ± 0.78 Ma); (c) postmagmatic argillization with epithermal gold-sulfide mineralization (82–80 Ma, the concordant age is 82.9 ± 2.7 Ma).  相似文献   

Nature of the X-ray Source in Supernova Remnant RCW103     

Sergei B. Popov 《Astrophysics and Space Science》2000,274(1-2):285-290

I discuss the nature of the compact X-ray source in the center of the supernova remnant RCW 103. Several models, based on the accretion onto a compact object are briefly discussed. I show that it is more likely that the central X-ray source is an accreting neutron star than an accreting black hole. I also argue that models of a disrupted binary system consisting of an old accreting neutron star and a new one observed as a 69-ms pulsar are most favored. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

On the periodical structures in populations of galaxies and of clusters of galaxies     

V. F. Litvin  F. M. Holzmann  B. S. Taibin  V. S. Popov  G. D. Poljakova 《Astronomische Nachrichten》1989,310(1):23-27

Analysing the distribution of the redshift of clusters of galaxies, obtained from the catalogue of SCHMIDT (1986), two already known periodical structures were confirmed and both periods were extended by a number of periods — approximately by two times (We elucidated 5 new periods in the first structure and 4 in the second.). The statistical significance of these structures was estimated to 0.01 in the first case and to 0.02 in the second one. Particularly, the second structure may be the largest known object in the Universe (about 900 Mpc at H = 75 km s^-1 Mpc^-1). These results agree with the predictions of the axion-dominated early Universe. In addition, we discovered periodical structures of an another type — in luminosity functions of galaxies, which are members of rich clusters. Bei der Analyse des Katalogs von SCHMIDT (1986) wurden zwei periodische Strukturen in den Verteilungen der Rotverschiebungen von Galaxienhaufen festgestellt. In den beiden Strukturen wurden 5 bzw. 4 neue Perioden beobachtet, weshalb sich die Periodenzahl in jeder der beiden Strukturen etwa verdoppelt hat. Die statistische Signifikanzen dieser Strukturen wurden zu 0.01 und 0.02 abgeschätzt. Möglicherweise entspricht die zweite Struktur dem größten bekannten Objekt des Weltalls (etwa 900 Mpc bei H = 75 km s^-1 Mpc^-1). Diese Resultate stützen die Theorie eines axiondominierten frühen Universums. Außerdem wurden weitere periodische Strukturen in der Leuchtkraftfunktion von Galaxien aus reichen Galaxien-haufen entdeckt.  相似文献   

Simulating the Propagation of Infrasonic Waves and Estimating the Energy of the Chelyabinsk Meteoroid Explosion Observed on February 15, 2013     

S.?N.?KulichkovEmail author  O.?Ye.?Popov  K.?V.?Avilov  I.?P.?Chunchuzov  O.?G.?Chkhetiani  A.?A.?Smirnov  V.?I.?Dubrovin  A.?A.?Mishenin 《Izvestiya Atmospheric and Oceanic Physics》2018,54(3):293-303

Results obtained from simulating the propagation of infrasonic waves from the Chelyabinsk meteoroid explosion observed on February 15, 2013, are given. The pseudodifferential parabolic equation (PDPE) method has been used for calculations. Data on infrasonic waves recorded at the IS31 station (Aktyubinsk, Kazakhstan), located 542.7 km from the likely location of the explosion, have been analyzed. Six infrasonic arrivals (isolated clearly defined pulse signals) were recorded. It is shown that the first “fast” arrival (F) corresponds to the propagation of infrasound in a surface acoustic waveguide. The rest of the arrivals (T1–T5) are thermospheric. The agreement between the results of calculations based on the PDPE method and experimental data is satisfactory. The energy E of the explosion has been estimated using two methods. One of these methods is based on the law of conservation of the acoustic pulse I, which is a product of the wave profile area S/2 of the signal under analysis and the distance to its source E _I [kt] = 1.38 × 10^–10 (I [kg/s])^1.482. The other method is based on the relation between the energy of explosion and the dominant period T of recorded signal E _T [kt] = 1.02 × (T [s]²/σ)^3/2, where σ is the dimensionless distance determining the degree of nonlinear effects during the propagation of sound along ray trajectories. According to the data, the explosion energy E _I,T ranges from 1.87 to 32 kt TNT.  相似文献   

Absorption of Photons from Distant Gamma-Ray Sources     

A. N. Popov  D. P. Barsukov  A. V. Ivanchik 《Astronomy Letters》2018,44(10):579-587

Being the largest gravitationally bound structures in the Universe, galaxy clusters are huge reservoirs of photons generated by the bremsstrahlung of a hot cluster gas. We consider the absorption of high-energy photons from distant cosmological gamma-ray sources by the bremsstrahlung of galaxy clusters. The magnitude of this effect is the third in order of smallness after the effects of absorption by the cosmic microwave background and absorption by the extragalactic background light. Our calculations of the effect of absorption by the bremsstrahlung of galaxy clusters have shown that this effect manifests itself in the energy range ~1–100 GeV and can be τ ~ 10^?5 in optical depth.  相似文献   

Simulating the influence of an atmospheric fine inhomogeneous structure on long-range propagation of pulsed acoustic signals     

S. N. Kulichkov  I. P. Chunchuzov  O. I. Popov 《Izvestiya Atmospheric and Oceanic Physics》2010,46(1):60-68

The results of simulating the influence of an atmospheric fine structure on the characteristics of acoustic signals propagating throughout the atmosphere for long distances from their sources are presented. A numerical model of an atmospheric fine inhomogeneous structure within the height range z = 20…120 km is proposed to perform calculations. This model and its numerical parameters are based on the current notions of the formation of an atmospheric fine structure due to internal gravity waves. The numerical calculations were performed using the parabolic-equation method. A spatial structure of the acoustic field and the structure of an acoustic signal at long distances from a pulsed source were calculated. It is shown that the presence of an atmospheric fine structure results in a scattering of acoustic signals and their recording in the geometric shadow region. The results of calculations of signal forms are in a satisfactory agreement with data on signals recorded in the geometric shadow region which is formed at a distance of about 300 km from an experimental explosion.  相似文献   

Structure of the current sheets in the near-Mars magnetotail. Maven observations     

E. E. Grigorenko  S. D. Shuvalov  H. V. Malova  V. Yu. Popov  V. N. Ermakov  E. Dubinin  L. M. Zelenyi 《Solar System Research》2017,51(5):347-361

During the last 15 years, the Current Sheets (CSs) have been intensively studied in the tail of the terrestrial magnetosphere, where protons are the dominated ion component. On the contrary, in the Martian magnetotail heavy ions (O⁺ and⁺ ₀) usually dominate while the abundance of protons can be negligible. Hence it is interesting to study the spatial structure and plasma characteristics of such “oxygen” CSs. MAVEN spacecraft (s/c) currently operating on the Martian orbit with a unique set of scientific instruments allows observation of the magnetic field and three-dimensional distribution functions of various ion components and electrons with a high time resolution. In this paper, we analyse nine intervals of the CSs observed by MAVEN in the near-Mars tail at the distances from the planet ~1.5–1R _M , where R _M is the radius of Mars. We analyse the spatial structure of the CSs and estimate their thickness for different magnetic configurations and relative abundance of the heavy and light ions in the sheets. It is shown that, similarly to the CSs in the Earth’s magnetotail, the thickness and complexity of the spatial structure of the Maritan CSs (i.e. the presence of embedded and / or peripheral current structures) depend on the magnetic configuration of the sheets, which, in turn, affects the fraction of the quasi-adiabatic particles in the CSs.  相似文献   

New observations and transit solutions of the inflated exoplanets HAT-P-40b and HAT-P-51b     

Diana P.Kjurkchieva  Nikola I.Petrov  Velimir A.Popov 《天文和天体物理学研究(英文版)》2021,(2):157-160

We present high-precision photometric observations of the transiting exoplanets HAT-P-40 b and HAT-P-51 b by the Rozhen 2-m telescope.The newly-observed transit of HAT-P-40 b is the first one with a complete curve.The orbital periods of the two targets were improved.We modeled the observed transits and found bigger stellar radii than those derived from the stellar models.The planet radii of HATP-40 b and HAT-P-51 b obtained from our transit solutions are bigger than the values calculated by the empirical relations for Jupiter-mass and Saturn-mass planets respectively.Their values reveal the highlyinflated nature of the two targets,especially that of HAT-P-51 b.We established that the best transit solutions correspond to a quadratic limb-darkening law.The fitted limb-darkening coefficients of HAT-P-40 are close to the theoretical ones while those of HAT-P-51 are a little different.The precise astrometric Gaia distances of the two targets are smaller by 6%–7%than the calculated values from the stellar models.We propose the Gaia distances to be used for improvement of the stellar models as well as for more reliable calculation of the parameters of the known exoplanets.  相似文献   

NSVS 2569022:a peculiar binary among W UMa stars with extremely small mass ratios     

Diana P.Kjurkchieva  Velimir A.Popov  Nikola I.Petrov 《天文和天体物理学研究(英文版)》2018,(10)

Photometric observations of the W UMa binary NSVS 2569022 are presented. The light curve solution reveals that both components are of F spectral type(temperatures T_1= T_2= 6100 K). NSVS2569022 undergoes a total eclipse of W subtype and the mass ratio is well-determined. Its extremely small value of only 0.077 implies that the target will probably experience instability and a possible merger. This value ranks NSVS 2569022 in sixth place among binaries with the smallest mass ratio.Based on an empirical relation of "period – total mass" for low mass-ratio binaries, we estimate the global parameters of NSVS 2569022: masses M_1= 1.17 M⊙and M_2= 0.09 M⊙; radii R_1= 1.19 R⊙and R_2= 0.38 R⊙; luminosities L_1= 1.73 L⊙and L_2= 0.17 L⊙. An analysis of the characteristics of binaries with extremely low-mass ratios is made. NSVS 2569022 turns out to be a peculiar binary among W UMa stars with extremely small mass ratios due to its unexpectedly small fill-out factor of only 0.014(slightly overcontact configuration).  相似文献   

Kinetic equations for ultrarelativistic particles in a Robertson-Walker universe and isotropization of relict radiation by gravitational interactions     

Yu. G. Ignat'ev  A. A. Popov 《Astrophysics and Space Science》1990,163(1):153-174

Kinetic equations for ultrarelativistic particles with due account of gravitational interactions with massive particles in the Robertson-Walker universe are obtained. On the basis of an exact solution of the kinetic equations thus obtained, a conclusion is made as to the high degree of the uniformity of the relict radiation on scales whih are less than 10.  相似文献