Revaluation of the natural-resource potential of Ukraine

We provide a rationale for the technique of revaluating the natural-resource potential which is built upon the natural crop yield of Ukrainian lands obtained, with the observance of rotation cropping and by implementing the complex of mechanical tillage operations without fertilizer application. An assessment is made of Ukraine’s natural-resource potential within the context of three physical-geographical countries, four zones, three subzones, and 14 krais.     

Dispersal of arbuscular mycorrhizal fungi and dark septate endophytes by Ctenomys cf. knighti (Rodentia) in the northern Monte Desert of Argentina

In arid and semi-arid environments, root-associated fungi may play a key role in plant communities (e.g., seedling establishment, nutrient acquisition, plant survival and heat tolerance). Several studies have shown the importance of small mammals as consumers and dispersal agents of mycorrhizal fungi spores in tropical and temperate ecosystems. However, little is known about the dispersal of infective propagules of endophytic fungi in arid and semi-arid ecosystems. This study analyzed the potential role of the subterranean rodent Ctenomys cf. knighti as a dispersal agent of root-associated fungi. In order to demonstrate this role, we analyzed: (1) the incidence of colonization of arbuscular mycorrhizae and dark septate endophytes on representative plant species of the Monte Desert; (2) the presence of fungal structures of arbuscular mycorrhizae and dark septate endophytes in C. cf. knighti fecal samples; and (3) the infectivity of the fungal propagules contained in the scat and their growth effects on nine native plant species. Data strongly suggest that this South American subterranean rodent may play a key role as a dispersal agent of arbuscular mycorrhizae and dark septate endophytes fungi in the arid environment of the northern Monte Desert of Argentina.     

Unique components of the WZ Sge-type dwarf nova SDSS J080434.20+510349.2

Detailed photometrical monitoring of the cataclysmic variable SDSS J080434.20+510349.2 began at the Crimean Astrophysical Observatory (Ukraine) and the Apache Point Observatory (United States) before the 2006 outburst, continued during the outburst, as well as the following two years. We established the unique nature of the primary and secondary components of the binary. We performed a comprehensive study of the white dwarf’s pulsations over the course of five months, two years after the 2006 outburst. It is shown that the most stable pulsations are equal to or double a period of 12.6 min. On the basis of all the available observations, more precise values for the orbital and the superhump periods were found to be 0.0590048(3) days and 0.059729(4) days, respectively. Our estimation of the mass of the secondary component lies in the range of solar mass from 0.037 to 0.087. This confirms the previous suggestion that the secondary component is most probably a brown dwarf.     

Could CoRoT-7b and Kepler-10b be remnants of evaporated gas or ice giants?

We present thermal mass loss calculations over evolutionary time scales for the investigation if the smallest transiting rocky exoplanets CoRoT-7b (∼1.68R_Earth) and Kepler-10b (∼1.416R_Earth) could be remnants of an initially more massive hydrogen-rich gas giant or a hot Neptune-class exoplanet. We apply a thermal mass loss formula which yields results that are comparable to hydrodynamic loss models. Our approach considers the effect of the Roche lobe, realistic heating efficiencies and a radius scaling law derived from observations of hot Jupiters. We study the influence of the mean planetary density on the thermal mass loss by placing hypothetical exoplanets with the characteristics of Jupiter, Saturn, Neptune, and Uranus to the orbital location of CoRoT-7b at 0.017 AU and Kepler-10b at 0.01684 AU and assuming that these planets orbit a K- or G-type host star. Our findings indicate that hydrogen-rich gas giants within the mass domain of Saturn or Jupiter cannot thermally lose such an amount of mass that CoRoT-7b and Kepler-10b would result in a rocky residue. Moreover, our calculations show that the present time mass of both rocky exoplanets can be neither a result of evaporation of a hydrogen envelope of a “Hot Neptune” nor a “Hot Uranus”-class object. Depending on the initial density and mass, these planets most likely were always rocky planets which could lose a thin hydrogen envelope, but not cores of thermally evaporated initially much more massive and larger objects.     

Solar wind induction in Mercury: Constraints on the formation of a magnetosphere

The discovery of Mercury's magnetosphere by Mariner 10 was surprising since the conventional view of regenerative planetary dynamos had been that the spin requirement would likely have been in excess of the observed spin rate of Mercury. Also internal fluid motions were not expected to be sufficiently large. This paper explores the alternative model of the formation of Mercury's magnetosphere via electromagnetic induction forced by the solar wind. It is shown, however, that the constraints are so severe as to limit severely the applicability of such a model. Although induction is easily observed on the Moon, the modification of the magnetic boundary condition associated with a plasma magnetosphere on Mercury rules out its formation via induction except for interplanetary driving fields which are decreasing in amplitude. That model is explored but retains the difficulty that induced magnetospheres tend to be of small radial and temporal extent compared to that inferred by Ness et al. for Mercury.     

Photometric Inference of the Corotation Radii of Ten Barred Galaxies

We have used photometric images of ten barred galaxies in the B and I bands to infer the geometrical and dynamical parameters of their bars: Their length, (R _bar), their strengths, (S _b), and their corotation radii, (R _CR).These parameters have been obtained studying azimuthal profiles from the B and I band images of the galaxies. We find that R _CR is in all cases slightly larger than R _bar, with mean values close to 1.2 R _bar. We have also found a dependence of the ratio R _CR/R _bar on S _bar. This revised version was published online in July 2006 with corrections to the Cover Date.     

Identification of some of the unidentified EIC-1 sources

We have identified 20 of the 75 unidentified Equatorial Infrared Catalogue Number-1 sources with stars in the BD Catalogue. Two of these are also found in the HD Catalogue.     

Comparative Analysis of a Transition Region Bright Point with a Blinker and Coronal Bright Point Using Multiple EIS Emission Lines

Since their discovery 20 year ago, transition region bright points have never been observed spectroscopically. Bright point properties have not been compared with similar transition region and coronal structures. In this work we have investigated three transient quiet Sun brightenings including a transition region bright point (TR BP), a coronal bright point (CBP) and a blinker. We use time-series observations of the extreme-ultraviolet emission lines of a wide range of temperature T (logT=5.3?–?6.4) from the EUV Imaging Spectrometer (EIS) onboard the Hinode satellite. We present the EIS temperature maps and Doppler maps, which are compared with magnetograms from the Michelson Doppler Imager (MDI) onboard the SOHO satellite. Doppler velocities of the TR BP and blinker are ≤?25 km?s^?1, which is typical of transient TR phenomena. The Doppler velocities of the CBP were found to be ≤?20 km?s^?1 with exception of those measured at logT=6.2 where a distinct bi-directional jet is observed. From an EM loci analysis we find evidence of single and double isothermal components in the TR BP and CBP, respectively. TR BP and CBP loci curves are characterized by broad distributions suggesting the existence of unresolved structure. By comparing and contrasting the physical characteristics of the events we find that the BP phenomena are an indication of multi-scaled self-similarity, given the similarities in both their underlying magnetic field configuration and evolution in relation to EUV flux changes. In contrast, the blinker phenomena and the TR BP are sufficiently dissimilar in their observed properties as to constitute different event classes. Our work is an indication that the measurement of similar characteristics across multiple event types holds class-predictive power, and is a significant step towards automated solar atmospheric multi-class classification of unresolved transient EUV sources. Finally, the analysis performed here establishes a connection between solar quiet region CBPs and jets.     

Evolving Photospheric Flux Concentrations and Filament Dynamic Changes

We analyze the role of weak photospheric flux concentrations that evolve in a filament channel, in the triggering of dynamic changes in the shape of a filament. The high polarimetric sensitivity of THEMIS allowed us to detect weak flux concentrations (few Gauss) associated with the filament development. The synoptic instruments (MDI, SOLIS) even if their sensitivity is much less than THEMIS were useful to follow any subsequent strengthening of these flux concentrations after their identification in the THEMIS magnetograms. We found that (1) the northern part of the filament develops an Hα barb at the same time that weak minority polarity elements develop near a plage; (2) a section in the southern part of the Hα filament gradually disappears and later reforms at the same time that several mixed-polarity magnetic elements appear, then subsequently cancel or spread away from each other. These changes correspond to increases in EUV emission, as observed by TRACE, EIT, and CDS. This suggests that the plasma is temporarily heated along the filament spine. An idealized sequence of force-free models of this filament channel, based on plasma-supporting magnetic dips occurring in the windings of a very weakly twisted flux tube, naturally explains the evolution of its southern part as being due to changes in the topology of the coronal magnetic field as the photospheric flux concentrations evolve.