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1.
E. P. Kurbatov 《Astronomy Reports》2007,51(12):957-966
We suggest a model for the star-formation function and the dissipation of turbulent energy of the interstellar medium. The star-formation function takes into account the effect of turbularization of the ISM. Applying the derived relations to a hierarchical scenario for the formation of galaxies makes it possible to explain the observed delay of star formation in the Galaxy, which corresponds to a range of stellar ages from 8–9 to 10–12 Gyr. 相似文献
2.
V. P. Yushkov M. A. Kallistratova R. D. Kouznetsov G. A. Kurbatov V. F. Kramar 《Izvestiya Atmospheric and Oceanic Physics》2007,43(2):168-180
The experience of long-term acoustic remote measurements of vertical wind-velocity profiles at two sites in Moscow is reported. Equipment performances and measurement conditions are described. Acoustic measurement features characteristic of a large city with high traffic noise and spurious reflections from buildings are discussed. Criteria and techniques of rejecting noisy and false signals are described as well as the methods of statistical data processing suitable in the case of a signal-to-noise ratio rapidly varying in time and a significant number of rejected signals. Preliminary results of measurements are given. 相似文献
3.
We study the evolution of the [O/Fe]-[Fe/H] relation and the dependence of the iron abundance on distance from the galactic plane z in a one-zone model for a disk galaxy, starting from the beginning of star formation. We obtain good agreement with the observational data, including, for the first time, agreement for the [Fe/H]-z relation out to heights of 16 kpc. We also study the influence of the presence of dark matter in the galaxies on the star-formation rate. Comparison of the observed luminosity of the Galaxy with the model prediction places constraints on the fractional mass of dark matter, which cannot be much larger than the fractional mass of visible matter, at least within the assumed radius of the Galaxy, ～20 kpc. We studied the evolution of disk galaxies with various masses, which should obey the Tully-Fisher relation, M ? R2. The Tully-Fisher relation can be explained as a combination of a selection effect related to the observed surface brightnesses of galaxies with large radii and the conditions for the formation for elliptical galaxies. 相似文献
4.
M. Siarkowski J. Sylwester J. Bąkała Ż. Szaforz M. Kowaliński Z. Kordylewski S. Płocieniak P. Podgórski B. Sylwester W. Trzebiński M. Stȩślicki K. J. H. Phillips O. V. Dudnik E. Kurbatov V. D. Kuznetsov S. Kuzin I. V. Zimovets 《Experimental Astronomy》2016,41(3):327-350
Interhelioprobe (IHP), an analogue to the ESA Solar Orbiter, is the prospective Russian space solar observatory intended for in-situ and remote sensing investigations of the Sun and the inner heliosphere from a heliocentric orbit with the perihelion of about 60 solar radii. One of several instruments on board will be the Bragg crystal spectrometer ChemiX which will measure X-ray spectra from solar corona structures. Analysis of the spectra will allow the determination of the elemental composition of plasma in hot coronal sources like flares and active regions. ChemiX is under development at the Wroc?aw Solar Physics Division of the Polish Academy of Sciences Space Research Centre in collaboration with an international team (see the co-author list). This paper gives an overview of the ChemiX scientific goals and design preparatory to phase B of the instrument development. 相似文献
5.
O. V. Dudnik M. Prieto E. V. Kurbatov S. Sanchez T. G. Timakova A. V. Spassky V. N. Dubina P. Parra 《Solar System Research》2013,47(1):58-65
The design concept and first set of results are presented for electronic modules of a laboratory prototype of the small-size satellite instrument SIDRA intended for measurements of charged particle fluxes in outer space. The working prototype consists of a detector assembly based on high-purity silicon and fast scintillation detectors, modules of analogue and digital processing, and a secondary power supply module. The first results are discussed of a Monte-Carlo simulation of the instrument with the use of the GEANT4 toolkit and of measurements of the main parameters of charge-sensitive pre-amplifiers, shapers, and peak detectors. Results of calibration measurements with the use of radioactive sources and beams of accelerated charged particles are presented. 相似文献
6.
Accretion disks in binary systems can experience hydrodynamical influences at both their inner and outer edges. The former is typical for protoplanetary disks around young T Tauri stars, while the latter is typical for circumstellar disks in close binaries. This influence excites perturbations with various scales and amplitudes in the disk. The nonlinear evolution of perturbations with a finite, but small amplitude against the background of a sub-Keplerian flow is investigated. Nonlinear effects at the fronts of perturbation waves lead to the formation of discontinuities in the density and radial velocity; i.e., to formation of shocks. The tangential flow in the neighborhood of the shock becomes equivalent to a flow in a boundary layer. Due to an instability of the tangential flow, the disk becomes turbulent. The characteristics of the turbulence depend on the parameters of the perturbations, but the Shakura–Syunyaev α parameter does not exceed ~0.1. 相似文献
7.
The interaction of ash flows with ridges 总被引：1，自引：0，他引：1
Using both laboratory experiments and theoretical models, we examine the different flow regimes that may develop when an
ash flow encounters a ridge. For very small ridges, all the flow may pass over the ridge. For intermediate-size ridges, the
flow may be partially blocked, with a fraction of the flow reflected upstream as a travelling bore. In this case, the remainder
of the flow, which does pass over the ridge, is hydraulically controlled at the ridge crest. Finally, if the ridge is sufficiently
high, then the flow will be totally blocked. New laboratory experiments show that the sedimentation patterns associated with
these flow regimes may be very different. Most importantly, flows that involve partial blocking and the formation of upstream
propagating bores display enhanced sedimentation upstream of the ridge, analogous to valley-ponded and caldera-fill deposits.
In contrast, under some circumstances, if the flow is able to scale a ridge, the deposit may be relatively unaffected by the
presence of the ridge. The minimum ridge height that leads to total blocking of the flow increases with mass eruption rate
and has a complex variation with distance from the source. In a one-dimensional channel, the minimum ridge height that causes
blocking increases with distance downstream. This is because the flow becomes less dense through sedimentation of particles
and entrainment of air and so requires less energy to scale a ridge of a particular height. In axisymmetric flow, the minimum
ridge height initially decreases with distance downstream as the flow spreads radially, but subsequently increases as the
flow becomes less dense through sedimentation and entrainment. A new quantitative model of dilute ash flows propagating over
ridges indicates that flows with mass fluxes in excess of 108–109 kg/s can partially scale barriers as high as 1000 m at distances of tens of kilometres from the source, whereas smaller flows
are likely to be totally blocked by such an obstacle. Our results shed new insight on the possible long-range transport mechanism
of several large flows including the Ata, Fisher and Aniakchak pyroclastic flows.
Received: 20 December 1996 / Accepted: 15 March 1998 相似文献
8.
A total of 24 tephra-bearing volcanic layers have been recognized between 550 and 987 m depth in the Siple Dome A (SDM-A) ice core, in addition to a number already recognized tephra in the upper 550 m (Dunbar et al., 2003, Kurbatov et al., 2006). The uniform composition and distinctive morphological of the particles composing these tephra layers suggest deposition as a result of explosive volcanic eruptions and that the layers therefore represent time-stratigraphic markers in the ice core. Despite the very fine grain size of these tephra (mostly less than 20 microns), robust geochemical compositions were determined by electron microprobe analysis. The source volcanoes for these tephra layers are largely found within the Antarctic plate. Statistical geochemical correlations tie nine of the tephra layers to known eruptions from Mt. Berlin, a West Antarctic volcano that has been very active for the past 100,000 years. Previous correlations were made to an eruption of Mt. Takahe, another West Antarctic volcano, and one to Mt. Hudson, located in South America (Kurbatov et al., 2006). The lowest tephra layer in the ice core, located at 986.21 m depth, is correlated to a source eruption with an age of 118.1 ± 1.3 ka, suggesting a chronological pinning point for the lower ice. An episode of anomalously high volcanic activity in the ice in the SDM-A core between 18 and 35 ka (Gow and Meese, 2007) appears to be related to eruptive activity of Mt. Berlin volcano. At least some of the tephra layers found in the SDM-A core appear to be the result of very explosive eruptions that spread ash across large parts of West Antarctica, off the West Antarctic coast, as well as also being recognized in East Antarctica (Basile et al., 2001, Narcisi et al., 2005, Narcisi et al., 2006). Some of these layers would be expected to should be found in other deep Antarctic ice cores, particularly ones drilled in West Antarctica, providing correlative markers between different cores. The analysis of the tephra layers in the Siple Dome core, along with other Antarctic cores, provides a timing framework for the relatively proximal Antarctic and South American volcanic eruptive events, allowing these to be distinguished from the tropical eruptions that may play a greater role in climate forcing. 相似文献
9.
A. V. Dudnik V. K. Persikov I. I. Zalyubovsky T. G. Timakova E. V. Kurbatov Yu. D. Kotov V. N. Yurov 《Solar System Research》2011,45(3):212-220
The STEP-F satellite telescope for measuring electrons and protons of the Photon scientific equipment is described. Its design
features are given. The device detects electrons, protons, and α-particles in the energy range 0.18–2.3, 7.4–55.2, and 298–160.0
MeV, respectively. Geometric factors vary in the range of 12.4–21.7 cm2 sr, depending on the energy of the particles. In addition, there are three channels of mixed recording of particles of different
types and channels of recording of the secondary electromagnetic radiation generated in the construction materials of the
device and spacecraft. Methods and results of the computer simulation of the passage of the particle through detector materials
are presented, along with configuration, calibration measurements, and tests (both standalone and integrated) within the complex
of scientific instrumentation and spacecraft. Updated data on geometric factors of the device and energy ranges of the direct
detection of charged high-energy particles and of channels of mixed recording of several types of particles are given. Special
software is described for the rapid analysis of the processed data of the STEP-F telescope, and the visualization of time
variations of particle fluxes with different time resolution in some periods of high solar activity and in its absence. 相似文献
10.
E. P. Kurbatov 《Astronomy Reports》2010,54(7):590-598
The ejection of stars from spheroidal and disk dwarf galaxies resulting from the decay of OB associations is studied. This
has substantial observational consequences for disk galaxies with escape velocities up to 20 km/s, or dynamical masses up
to 108
M
⊙. The ejection of stars can (i) reduce the abundances of the products of Type Ia supernovae and, to a lesser degree, Type
II supernovae, in disk stars, (ii) chemically enrich the galactic halo and intergalactic medium, (iii) lead to the loss of
50% of the stellar mass in galaxies with masses ∼107
M
⊙ and the loss of all stars in systems with masses ≲105
M
⊙, (iv) increase the mass-to-luminosity ratio of the galaxy. 相似文献