Boltzmann statistical theory and asymptotics of the temperature distribution of spontaneous jets in the convective atmospheric surface layer

An ensemble of convective thermals is distinguished from the surface layer of penetrative turbulent convection over a heated horizontally uniform surface. A statistical model of the ensemble of convective thermals is developed that uses the idea of entropy in the Boltzmann-Jaynes form. The distribution of thermals by potential energies is shown to display an entropy maximum. On the basis of the Boltzmann distribution by potential energies, the temperature distribution of spontaneous jets is obtained and found to be consistent with known experimental data.     

Mineralogical-geochemical features of sulfide ores from the Broken Spur hydrothermal vent field

A representative collection of hydrothermal sediments was sampled practically from all the hydrothermal mounds of the Broken Spur hydrothermal vent field from the Mir manned submersibles during three cruises of R/V Akademik Mstislav Keldysh. Mineral associations characteristic of different morphological types of sulfide ores from hydrothermal pipes, plates, and diffusers are assessed. Particular attention is paid to the distribution of minor elements and their distribution patterns determined by the mineralogical zonation. The measured isotopic value of the sulfur in the sulfide minerals appeared to vary from 0.4 to 5.2‰, which indicates their similarity with the ores from the Snake Pit vent field and is related to the dilution of hot ore-bearing solutions by seawater and reduction of the water sulfate ions to H₂S with a heavy isotopic composition.     

Investigation of heliogeoactivity impact on the dynamics of orbital parameters of Earth’s artificial satellites. I

The influence of active processes on the Sun and their response on the dynamics of Earth’s artificial satellites has been investigated. The relationship between the characteristics of solar activity and variations of the periods P of the orbital motion of Earth’s artificial satellites has been found. These variations mainly indicate the variations in the Earth’s atmosphere density caused by solar activity (index F_10.7) and geomagnetic activity (ΣK_p index). High values of the correlation coefficients between P and ^F_10.7 (–0.77…–0.91) and between P and ΣK_p (–0.67…–0.89) exhibit significant effect of solar and geomagnetic activity on the orbital periods of satellites.     

Numerical Instruments for the Analysis of Secular Dynamics of Exoplanetary Systems

A review is given of modern numerical methods for the analysis of resonant and chaotic dynamics: calculation of the Lyapunov characteristic exponents, the MEGNO method, and the maximum eccentricity method. These methods are used to construct stability diagrams for the planetary systems γ Cep, HD 196885, and HD 41004. The diagrams are analyzed to determine the most probable values taken by the orbital parameters of the exoplanets and obtain estimates for the Lyapunov time of their orbital dynamics. The stability diagrams constructed using the different methods are compared to analyze their effectiveness in the study of secular dynamics of exoplanetary systems.     

Investigation of the atmospheric water-vapor content in Crimea via long-term photometric solar observations

Water-vapor content determination via solar-radiation absorption measurement in the watervapor absorption band ρ is described. The investigation was carried out with an automatic solar photometer, making it possible to record solar radiation in the band ρ and adjacent absorption-free spectrum sections. Regular observations have been performed in Crimea (Simferopol, 44.7 N and 34.1 E) from 2001 to the present. According to the observation data, the water-vapor content W in the atmosphere of Crimea is seasonally dependent, while the annual average value is almost constant.     

On determination of low oxygen concentrations with Winkler technique

The accuracy and detection limit of the oxygen technique is an actual problem in studying the processes that occur in the redox zone. The formal accuracy of the Winkler technique is 1 μM (0.02 mL L⁻¹) and its detection limit is about 3.0 μM (0.06 mL L⁻¹). These values are significantly higher than the similar characteristics (in molar concentrations) for such parameters as the hydrogen sulphide, nitrates, manganese, and others. In this work, we describe some recommendations for increasing the accuracy of the Winkler technique. The results of the application of these recommendations for the suboxic zone of the Black Sea are presented. During the 100th cruise of the R/V Professor Shtokman, argon-filled balloons were attached to the upper valves of Niskin bottles during the sampling, which allowed protecting the samples from contamination with atmospheric oxygen. The titration was performed with an automatic Metrohm Titrino burette with potentiometric end point detection. That allowed us to significantly increase the accuracy and decrease the detection limit compared with the visual techniques. The oxidized forms of metals present in the sea water (Mn(IV), Mn(III); Fe(III)) were measured, which allowed us to correct the Winkler technique calculations for the oxidizers. The studies performed during the 100th cruise of the R/V Professor Shtokman confirmed the absence of a layer of the coexistence of oxygen and hydrogen sulphide.     

Investigation of the polarization observed in infrared absorption bands in the spectra of protostars

We investigate the linear polarization in the two deepest infrared absorption bands observed in the spectra of protostars, the water-ice band with the center near 3.1 μm and the silicate band with the center near 9.7 μm, using a core-mantle confocal spheroid model with various axial ratios a/b and relative volumes of the core material. We consider the effect of the grain shape, structure, and type (oblate, prolate) as well as the type of grain orientation and its location relative to the incident ray of light and the magnetic field direction on the central wavelengths of the two bands and the polarizability in the bands. We have found that the observed relationships between the polarizability in the bands and the ratio of their optical depths at the band centers can be explained if we choose slightly oblate or prolate particles (a/b ≲2 for the silicate band and 1.3 ≲ a/b ≲ 2 for the ice band). For any type of orientation, the core-mantle confocal spheroid model requires different axial ratios for the ice and silicate bands to account for the observed polarization. We show that picket-fence-oriented particles can explain the observed polarization in the ice band at angles α between the particle rotation axis and the incident ray ≳30° and in the silicate band at any α. Perfectly Davis-Greenstein-oriented particles can explain the observed polarization in the ice band at angles Ω between the line of sight and the magnetic field direction ≳60° and in the silicate band at any Ω. The orientation parameter ζ (imperfect Davis-Greenstein orientation) must be no more than 0.5 (oblate particles) and 0.1 (prolate particles) for the ice band and can be arbitrary for the silicate band. Original Russian Text ? T.V. Zinov’eva, 2006, published in Pis’ma v Astronomicheskiĭ Zhurnal, 2006, Vol. 32, No. 10, pp. 748–766.     

Origin and evolution of the long-period comets

We consider the changes of cometary perihelion distances as a process of diffusion in the value of q, due to perturbations by stars. We find more comets at large q values than is observed. This suggests that a large number of long-period comets is not observed.     

Populating the asteroid belt from two parent source regions due to the migration of giant planets—“The Grand Tack”

Abstract– The asteroid belt is found today in a dramatically different state than that immediately following its formation. It is estimated that it has been depleted in total mass by a factor of at least 1000 since its formation, and that the asteroids’ orbits evolved from having near‐zero eccentricity and inclination to the complex distributions we find today. The asteroid belt also hosts a wide range of compositions, with the inner regions dominated by S‐type and other water‐poor asteroids and the outer regions dominated by C‐type and other primitive asteroids. We discuss a model of early inner solar system evolution whereby the gas‐driven migration of Jupiter and Saturn brings them inwards to 1.5 AU, truncating the disk of planetesimals in the terrestrial planet region, before migrating outwards toward their current locations. This model, informally titled “The Grand Tack,” examines the planetary dynamics of the solar system bodies during the final million years of the gaseous solar nebula lifetime—a few million years (Myr) after the formation of the first solids, but 20–80 Myr before the final accretion of Earth, and approximately 400–600 Myr before the Late Heavy Bombardment of the inner solar system. The Grand Tack attempts to solve some outstanding problems for terrestrial planet formation, by reproducing the size of Mars, but also has important implications for the asteroid population. The migration of Jupiter causes a very early depletion of the asteroid belt region, and this region is then repopulated from two distinct source regions, one inside the formation region of Jupiter and one between and beyond the giant planets. The scattered material reforms the asteroid belt, producing a population the appropriate mass, orbits, and with overlapping distributions of material from each parent source region.