Tidal dwarfs in the M81 group: the second generation?

We present a quantitative star formation history derivation of the four suspected tidal dwarf galaxies in the M 81 group: Holmberg IX, BK3N,Arp-loop (A0952+69) and Garland using HST/WFPC2 images of these galaxies. We construct a library of synthetic Colour-Magnitude Diagrams(CMDs) based on theoretical isochrones and data-derived determinations of photometric errors. These synthetic CMDs were combined linearly andχ²-compared to observed photometry. All the galaxies show continuous star formation between about 20 and 200 Myr ago with star formation rates between 7.5⋅10^-3 M_⊙/yr and 7.67⋅10^-4 M_⊙/yr. The metallicity of the detected stars is spanning rather a wide range, being lower than solar abundance. We suppose, that all the galaxies were formed out of material from metal-poor outer part of the giant spiral galaxy M81after tidal interaction about 200 Myr ago. However, this suggestion requires significantly more deep color-magnitude diagrams to be sure with the scenario of the galaxy evolution. This revised version was published online in July 2006 with corrections to the Cover Date.     

The peculiarities of rotation of the solar polar regions

The sidereal rotation rate of the high-latitude solar regions is examined using long-lived photospheric polar faculae. The observations were carried out with the photoheliograph of Kislovodsk Mountain Station of the Pulkovo Observatory from 1982 to 1986. The following facts have been established: (a) There is a differential rotation of the polar faculae close to the maximum of solar activity, while the amount of latitude gradient of solar rotation decreases towards the sunspot minimum; (b) small differences of rotation in the northern and southern hemispheres of the Sun are observed; (c) some deviations of differential rotation curves constructed for each Carrington rotation from the mean curve of differential rotation are revealed. The total amplitude of the maximum positive and negative excesses is about 40–50 m s^–1. The positive surplus velocities of solar rotation (the amplitude of which is about 20–25 m s^–1) move in the form of a wave from heliographic latitudes 40° with a velocity of 1.6 m s^–1. The latitude width of this flow is B 15°. This wave of abnormally high velocity starts in the year of minimum solar activity and reaches the pole 11 years later. The picture is symmetrical relative to the equator.     

The Effect of Alongshore Protection Structures on Shore Dynamics

A mathematical model of the seashore dynamics is considered. The model describes the seashore protection against destruction by alongshore through structures, underwater trenches, and artificial islands. The results of model calculations are presented and correlated with the data of measurements made on hydraulic models.     

The phosphate-containing interlayers of the Bazhenov Formation as potential reservoirs

The possible reservoir type of the Bazhenov Formation relative to the intervals enriched in phosphates (apatite varieties) is described in this work. The phosphate rocks are characterized by a highly developed pore space; their porosity can reach up to 14%. Along with this, these rocks have explicit geochemical characteristics of oil-reservoir rocks in comparison with other rock samples in the well. As an example, the productivity index and oil-saturation index for phosphates are twice as high as the background values. The composition of such rocks can slightly vary: fluorine can be observed in phosphate minerals, while the rock is always enriched in organic matter (>8 wt %).     

Holocene overbank deposition in the drainage basin of Lake Khanka

Overbank deposits in the Komissarovka River valley consist of alternating silt, clay silt, sand, and soils produced by lacustrine, alluvial, and aeolian deposition and by soil formation. Silt and sand layers in the lower part of the section correlate with the events of Early Holocene transgression and Middle Holocene regression of Lake Khanka. Deposition in the lowermost reaches of the Komissarovka River provides a faithful record of local Holocene landscapes controlled by level changes in Lake Khanka.     

The Composition and Reservoir Properties of the Deposits of the Bazhenov Formation in the Central Part of the Tundrin Depression

The section structure was characterized according to the lithological and petrophysical studies of the core from the Bazhenov Formation that has been uncovered in the central part of the Tundrin Depression. The productive oil intervals where the reservoirs of the pore and fissure-pore types occur were identified.     

The neotectonics and geodynamics of the Lower Oka Region (East European Craton)

The neotectonic structures of the Lower Oka (Nizhneokskii) Region formed under different geodynamic conditions. This is attested by the morphology, orientation, internal structure, and jointing of the structures. The Oka-Tsna arc formed under the effect of tension from an inner source on the one hand and stress from the Alpian belt on the other hand. The latitudinally-oriented structures of the northwestern slope of the Tokmovo arc emerged as a result of uplift and widening. Both types of structure are combined within the limits of the Oka-Murom trough, which is a geodynamically active zone.     

Assessment of the influence of air invasions from the upper troposphere on the CO total column amount in the St. Petersburg region

The influence of air invasions from the upper troposphere on the CO total column amount is studied on the basis of spectroscopic measurements of the CO total column amount, backward trajectories of air-mass motions (the HYSPLIT model), and meteorological data. It is shown that the observed invasions of substratospheric and upper-troposphere air masses determine the minimum CO total column amount in late January-late March. The invasion of air masses from the upper troposphere can result in a decrease in the CO total column amount to 30% (of its mean values). Using January 31, 2000, as an example, we show the influence of the invasion of Arctic air masses from the upper troposphere on the CO total column amount in the St. Petersburg region: the results of measurements of the CO total column amount in the St. Petersburg region and at the Kiruna polar station (NDACC) are in agreement to within 1% if the vertical transport of air masses is taken into account. Thus, for a correct combined analysis of measurement data on the CO total column amount for different observation stations, it is necessary to use data on air-mass trajectories.     

Studying seasonal variations in carbonaceous aerosol particles in the atmosphere over central Siberia

The results of 2-year (2010–2012) measurements of the concentrations of organic carbon (OC) and elemental carbon (EC), which were taken at the Zotino Tall Tower Observatory (ZOTTO) Siberian background station (61° N, 89° E), are given. Despite the fact that this station is located far from populated areas and industrial zones, the concentrations of OC and EC in the atmosphere over boreal forests in central Siberia significantly exceed their background values. In winter and fall, high concentrations of atmospheric carbonaceous aerosol particles are caused by the long-range transport (~1000 km) of air masses that accumulate pollutants from large cities located in both southern and southwestern regions of Siberia. In spring and summer, the pollution level is also high due to regional forest fires and agricultural burning in the steppe zone of western Siberia in the Russian–Kazakh border region. Background concentrations of carbonaceous aerosol particles were observed within relatively short time intervals whose total duration was no more than 20% of the entire observation period. In summer, variations in the background concentrations of OC closely correlated with air temperature, which implies that the biogenic sources of organic-particle formation are dominating.     

Date of minimum of the “protracted” solar cycle 23

We offer an interpretation of the now widely discussed protracted onset of the epoch of solar activity minimum after cycle 23. The interpretation appeals to the Gnevyshev-Ohl rule, but in the context of a new statistical quantity-the product of the cycle amplitude by its duration. Considering this quantity, which has the same physical meaning as that of the integrated characteristic used by Gnevyshev and Ohl, yields a probable estimate for the onset of the minimum of the current cycle in the interval 2009.0–2012.4.