Discovery of a Planar Waveguide for an X-Ray Radiation

A simple model of X-Ray standing waves (XSW) formation in the slit of a planar waveguide of X-Ray radiation beam for the angle area restricted by the critical total reflection angle is developed. It is shown that the model is true for a case of the Bragg reflection. The conditions required for XSW to appear in the space between two polished parallel plane plates are formulated and a slit size interval conforming to these conditions is evaluated. A mechanism of a XSW intensity decrease in a planar waveguide is proposed. This mechanism explains a high efficiency of slitless collimator application for the transportation of narrow X-Ray beams. Some recommendations on the application of the planar X-Ray waveguide in X-Ray structural and spectral studies of surface are presented.Comment: 15 pages, 2 figures, 1 tabl

Riemannian Spin(7) holonomy manifold carries octonionic-Kahler structure

We prove that Riemannian $Spin(7)$ holonomy manifolds carry octonionic-K\"{a}hler structure.Comment: 5 page

Symplectic analog of Calabi's conjecture for Calabi--Yau threefolds

In this paper we state an analog of Calabi's conjecture proved by Yau. The difference with the classical case is that we propose deformation of the complex structure, whereas the complex Monge--Amp\`{e}re equation describes deformation of the K\"{a}hler (symplectic) structure.Comment: 4 pages. This is a revised version of "Mirror Kaehler potential on Calabi-Yau threefolds" arXiv:1110.473

Metallicity and ionization state of the gas in polar-ring galaxies

The ionization state and oxygen abundance distribution in a sample of polar-ring galaxies (PRGs) were studied from the long-slit spectroscopic observations carried out with the SCORPIO-2 focal reducer at the Russian 6-m telescope. The sample consists of 15 PRGs classified as `the best candidates' in the SDSS-based Polar Ring Catalogue. The distributions of line-of-sight velocities of stellar and gaseous components have given kinematic confirmation of polar structures in 13 galaxies in the sample. We show that ionization by young stars dominates in the external parts of polar discs, while shocks have a significant contribution to gas excitation in the inner parts of polar structures. This picture was predicted earlier in a toy model implying the collision between gaseous clouds on polar orbits with the stellar disc gravitational potential well. The exception is a moderately inclined ring to the host galaxy NGC 5014: the accreted gas in the centre has already settled on the main plane and ionized by young stars, while the gas in the internal part of the ring is excited by shocks. The present study three times increases the number of polar structures with an available oxygen abundance estimation. The measured values of the gas metallicity almost do not depend on the galaxy luminosity. The radial [O/H] gradient in the considered polar rings is shallow or absent. No metal-poor gas was detected. We ruled out the scenario of the formation of polar rings due to cold accretion from cosmic filaments for the considered sample of PRGs.Comment: 13 pages, accepted for publication in MNRA

Memory effects in permalloy-niobium hybrid structures

The kineticts of magnetization reversal of stripe-shaped permalloy-niobium hybrid nanofilms is studied in 6-300 K temperature range by means of magneto-optics visualization technique. The niobium influence on magnetic domain walls type and on magnetic domain structure of permalloy via the interface quality and via the distortion of stray fields is found. The memory effect, which is the superconducting niobium memory about an initial magnetic domain structure of permalloy at cooling below T_c, is found. The memory is razed only by hybrid heating over T_c

Current and field stimulated motion of domain wall in narrow permalloy stripe

Of the new types of cryoelectronic devices under development, including phase shifters, giant magnetoresistance switches, diodes, transistors, and memory cells, some are based on hybrid superconductor-normal metal or superconductor-ferromagnet films. Control of these devices is realized by means of pulses of voltage, light, or magnetic field. Spin-polarized current may be used to switch low-temperature devices, as in spin-electronic devices. In the superconducting layer, the current is dissipation less, which would bring large reduction of energy consumption. We demonstrate that mag-netic domain walls in bilayer niobium-permalloy stripes are shifted by electrical current along the stripe even at low tem-perature, with the niobium in the superconducting state. The wall motion in response to current pulses is quite different from that induced by a magnetic field pulses only. The effect could be used to create a new type of sequentially switched serial devices because of very high value of the wall velocity, which excides by many orders of magnitude the velocity of the wall moved with magnetic field pulses.Comment: 5 pages, 6 figure

Super pulses of orbital angular momentum in fractional-order spiroid vortex-beams

We consider optical properties of Hypergeometric-Gaussian beam compositions with spiral-like intensity and phase distributions that were called the spiroid beams. Their orbital angular momentum as a function of a fractional-order topological charge has a chain of supper-pulses (bursts and dips).The form of the supper-pulses can be controlled by the spiral parameters. Such a phenomenon can be used in optical switches and triggers for optical devices and communication systems.Comment: 4 pages, 7 figure

Study of CME properties using high resolution data

The joint use of high-resolution data from PROBA2 and SDO satellites and LASCO/SOHO coronographs enabled us to examine early stages of initiation and propagation of six limb CMEs registered in June 2010 - June 2011. For five events under consideration, the CME initiation is marked by filament (prominence) eruption or by a loop-like structure having another nature. Subsequently, several loop-like structures having higher brightness and following each other at different velocities appear in the region of the CME initiation. The CME frontal structure is formed by these loop-like structures. The time-dependent velocities and acceleration of the ejection front have been obtained for all CMEs under consideration. We have drawn a conclusion about the possible existence of two CME types dependent on the time profile of their velocity. The first CME type comprises the ejections whose velocity decreases abruptly by more than 100 km/s after having reached the maximum; it thereupon passes to slow deceleration/variation. The second CME type is formed by the ejections whose velocity varies insignificantly after reaching the maximum. The CME angular size is shown to increase up to threefold at the initial stage of propagation; it increases twofold 3.5-11 minutes after the first measurement of this parameter. When considering 3 CMEs, we see that their broadening exceeds their extension in the longitudinal direction during a certain period of time at the initial propagation stage.Comment: 16 pages, 8 figure

Origin of a CME-related shock within the LASCO C3 field-of-view

We study the origin of a CME-related shock within the LASCO C3 field-of-view (FOV). A shock originates, when a CME body velocity on its axis surpasses the total velocity $V_A + V_{SW}$, where $V_A$ is the Alfv\'en velocity, $V_{SW}$ is the slow solar wind velocity. The formed shock appears collisionless, because its front width is manifold less, than the free path of coronal plasma charged particles. The Alfv\'en velocity dependence on the distance was found by using characteristic values of the magnetic induction radial component and of the proton concentration in the Earth orbit, and by using the known regularities of the variations in these solar wind characteristics with distance. A peculiarity of the analyzed CME is its formation at a relatively large height, and the CME body slow acceleration with distance. We arrived at a conclusion that the formed shock is a bow one relative to the CME body moving at a super Alfv\'en velocity. At the same time, the shock formation involves a steeping of the front edge of the coronal plasma disturbed region ahead of the CME body, which is characteristic of a piston shock

Search for gas accretion imprints in voids: I. Sample selection and results for NGC 428

We present the first results of a project aimed at searching for gas accretion events and interactions between late-type galaxies in the void environment. The project is based on long-slit spectroscopic and scanning Fabry-Perot interferometer observations performed with the SCORPIO and SCORPIO-2 multimode instruments at the Russian 6-m telescope, as well as archival multiwavelength photometric data. In the first paper of the series we describe the project and present a sample of 18 void galaxies with oxygen abundances that fall below the reference `metallicity-luminosity' relation, or with possible signs of recent external accretion in their optical morphology. To demonstrate our approach, we considered the brightest sample galaxy NGC 428, a late-type barred spiral with several morphological peculiarities. We analysed the radial metallicity distribution, the ionized gas line-of-sight velocity and velocity dispersion maps together with WISE and SDSS images. Despite its very perturbed morphology, the velocity field of ionized gas in NGC 428 is well described by pure circular rotation in a thin flat disc with streaming motions in the central bar. We also found some local non-circular gas motions clearly related to stellar feedback processes. At the same time, we revealed a circumnuclear inclined disc in NGC 428 and a region with significant residual velocities that could be considered as a result of a recent (<0.5 Gyr) accretion event. The observed oxygen abundance gradient does not contradict this conclusion.Comment: Accepted for publication in MNRAS; 13 pages, 10 figures, 4 table