Determining basic characteristics of stars from evolutionary computations

A technique for determining a star’s radius from its atmospheric characteristics (effective temperature, surface gravity, and metallicity) is realized based on modernmodel computations of the stellar internal structure and evolution. The atmospheric characteristics can also be used to find the mass and luminosity of the star. The star’s rate of evolution and the initial mass function are taken into account when determining the stellar characteristics, increasing the correctness of the results. Computations of stellar evolution of with and without the stellar rotation taken into account make it possible to remove ambiguity due to missing data on the star’s rotational velocity. The results are checked and uncertainties estimated using stars occupying two heavily populated regions in the Hertzsprung–Russell diagram that have been well studied using various methods: the main sequence and red giant branch. Good agreement with the observations is achieved; there are almost no systematic deviations of the derived point estimates of the fundamental characteristics. The metallicities of the individual components of eclipsing variable stars are estimated using observational data on for such stars displaying lines of both components in their spectra. These metallicities were determined as a function of the stellar masses in a way that eliminates systematic deviations in the derived fundamental characteristics.     

Geographical factors of the abundance of flora in Russian cities

Doklady Earth Sciences - An analysis of data on the species abundance of flora in 89 cities (urban flora) of the Russian Federation facilitated determination of its main factors. It has been...     

Diagnostic modelling of within-water processes in reservoirs

The objectives of diagnostic calculations using mathematical models of reservoirs are formulated. The structure of a box hydrological model GMV-MGU is described, and the results of calculation of daily water balance, internal heat exchange structure, and heat balance of individual areas in the Mozhaisk and Rybinsk reservoirs are given. First results of calculation of variations in mean daily phytoplankton biomass in the near-dam pool of a weakly eutrophic water body in period of spring (diatoms) and summer (blue-green) blooming are presented.     

Estimation of the ozone decrease possibility in the lower part of the <Emphasis Type="Italic">D</Emphasis> region under the action of a powerful radiowave

The possibility of the influence of a powerful radiowave on the ozone concentration in the lower part of the ionospheric D region is discussed on the basis of experiments at the Sura heating facility in March 2009, the results of which were published relatively recently by a group of authors. The results, which were obtained with the use of exact equations of the mesospheric ozone photochemistry, substantially disagree with some conclusions derived by the authors but do not completely deny their hypothesis on the possible influence on the ozone of internal gravity waves formed at heights of the ionospheric E region.     

The Effect of Aggregation of Impurity Nitrogen on Diamond X-Ray Luminescence

Two samplings of 65 diamond crystals divided by the intensity of a slow X-ray luminescence component are studied from the Arkhangel’skaya and Karpinskogo-1 pipes. IR and EPR spectroscopies revealed a relationship between the nitrogen A and P2 centers of the diamonds and the presence of a slow X-ray luminescence component. Its absence in most diamonds with high content of P1 (C) centers is explained by the low number of A and P2 centers.     

Delineation of Rajmahal basaltic flows,inter-trappeans and associated coal layers using Audio-magneto-telluric method

The extensive volcanic activity of Rajmahal occurred during early Cretaceous (~117 Ma). Potentially perspective Gondawana sediments containing coal seam is partially covered by these basalts. Basalts as well as coal are already known to be of immense economic importance over Rajmahal traps. The present study mainly deals with delineation of basaltic lava flows and associated coal layers using the Audio-magneto-telluric (AMT) study in the south central region of Rajmahal traps near Suri, West Bengal, India. Initially, the field situations have been simulated using forward model with top alluvium cover followed by basaltic lava flows, a wedge shaped inter-trappean sedimentary formation with second basaltic lava flows and basement at the bottom. The model was constrained using available litholog. The model study reveals the presence of moderately resistive basalts, relatively conductive inter-trappeans and the basement, except the top alluvium layer and thin inter-trappeans. Subsequently, threeAMT sounding have been carried out over Cholaguria, Hatgacha and Pachami, Suri, West Bengal. The field AMT study reveals three basaltic lava flows with varying thickness from ~40m to ~350m and composite thickness of ~620m to ~640m, which match well with the published borehole litholog. The inter-trappeans have been identified at 500m to 620m, 310m to 400m and 500m to 640m depths over Cholaguria, Hatgacha and Pachami, respectively. It is interesting to mention that the identified inter-trappeans are inferred to be coal/shaly-coal which are matching very well with the published borehole lithologs.     

Simulation of an in situ iron removal test

This article outlines the main mechanisms for in-situ removal of iron from groundwater. The dependence of ferrous iron kinetic oxidation by dissolved oxygen on the temperature and pH in bicarbonate near neutral groundwater was investigated. The dependence of oxygen consumption efficiency on the iron sorption coefficient, pH, and temperature of groundwater was obtained as a result of modeling of the one well in-situ iron removal test in the Amurskiy water intake facilities.     

Implications of the colour distribution in the galaxy M82

Photographic measurements of the colour distribution in the irregular galaxy M82 are presented and interpreted in terms of a model of that galaxy. Two alternative models are discussed. In the first the galaxy consists of a disc of highly reddened OB-stars, whose scattered light is also seen in the halo, and a bulge of less reddened A—F stars. The direction of the inclination of the system, as inferred from this model, is opposite to that of LYNDS and SANDAGE (1963). The alternative inclination (second model) may possibly be preserved if one assumes a central dust ellipsoid reemitting scattered light from a central source of OB stars. If the velocities of the line emitting material refer to scattering particles, an inward motion of them is more probable than an outward one, irrespectively of the model, and the (dust) halo of the galaxy is probably contracting.     

Minimum on the light curve of the classical symbiotic star AS 338 in 1999

We present our UBVRI photometry and spectroscopy of AS 338 performed in 1999–2000. Another eclipse of the hot component in this symbiotic binary system, the deepest one ever observed, occurred in September 1999. The U brightness declined by ～2^m, the Hβflux decreased by a factor of ～2.3, and the [O III]γ5007 flux did not change. The hot component is eclipsed at orbital phases ?≈0.045–0.057. The U-B color index begins to appreciably fluctuate during an eclipse of the hot component and its circumstellar envelope. About 100 days after a strong outburst of 1995, the mean UBV brightness of AS 338 declined linearly in the ensuing five years at the same rate in all bands (ΔU/Δt≈10^?3 mag/day). The brightness of the outer, uneclipsed parts of the circumstellar envelope also decreased, which is attributable to a reduction in the luminosity of the hot component against the rise in its temperature. The appearance of He II lines has not yet been recorded, though the optical brightness of AS 338 has already dropped by ～2^m after the outburst.