3,984 research outputs found
Superbroad Component in Emission Lines of SS 433
We have detected new components in stationary emission lines of SS 433; these
are the superbroad components that are low-contrast substrates with a width of
2000--2500 km s-1 in He I and H and 4000--5000 km s-1 in
He II . Based on 44 spectra taken during four years of
observations from 2003 to 2007, we have found that these components in the He
II and He I lines are eclipsed by the donor star; their behavior with
precessional and orbital phases is regular and similar to the behavior of the
optical brightness of SS 433. The same component in H shows neither
eclipses nor precessional variability. We conclude that the superbroad
components in the helium and hydrogen lines are different in origin. Electron
scattering is shown to reproduce well the superbroad component of H at a
gas temperature of 20--35 kK and an optical depth for Thomson scattering 0.25--0.35. The superbroad components of the helium lines are probably
formed in the wind from the supercritical accretion disk. We have computed a
wind model based on the concept of Shakura-Sunyaev supercritical disk
accretion. The main patterns of the He II line profiles are well reproduced in
this model: not only the appearance of the superbroad component but also the
evolution of the central two-component part of the profile of this line during
its eclipse by the donor star can be explained.Comment: 17 pages, 13 figures, 2 tables, published in Astronomy Letters, 2013,
vol. 39, N 12, pp. 826 - 84
Deformed Oscillator Algebras and Higher-Spin Gauge Interactions of Matter Fields in 2+1 Dimensions
We formulate a non-linear system of equations which describe higher-spin
gauge interactions of massive matter fields in 2+1 dimensional space-time and
explain some properties of the deformed oscillator algebra which underlies this
formulation. In particular we show that the parameter of mass of matter
fields is related to the deformation parameter in this algebra.Comment: LaTex, 12 pages, no figures; Invited talk at the International
Seminar Supersymmetry and Quantum Field Theory dedicated to the memory of
Dmitrij V. Volkov; Kharkov, January 1997; to appear in the proceeding
Dynamical lattice instability versus spin liquid state in a frustrated spin chain system
The low-dimensional s=1/2 compound (NO)[Cu(NO3)3] has recently been suggested
to follow the Nersesyan-Tsvelik model of coupled spin chains. Such a system
shows unbound spinon excitations and a resonating valence bond ground state due
spin frustration. Our Raman scattering study demonstrates phonon anomalies as
well as the suppression of a broad magnetic scattering continuum for
temperatures below a characteristic temperature, T<T*=100K. We interpret these
effects as evidence for a dynamical interplay of spin and lattice degrees of
freedom that might lead to a further transition into a dimerized or
structurally distorted phase at lower temperatures.Comment: 5 pages, 6 figure
Quantum reflection of antihydrogen from a liquid helium film
We study the quantum reflection of ultracold antihydrogen atoms bouncing on
the surface of a liquid helium film. The Casimir-Polder potential and quantum
reflection are calculated for different thicknesses of the film supported by
different substrates. Antihydrogen can be protected from anni- hilation for as
long as 1.3s on a bulk of liquid 4He, and 1.7s for liquid 3He. These large
lifetimes open interesting perspectives for spectroscopic measurements of the
free fall acceleration of antihydrogen. Variation of the scattering length with
the thickness of a film of helium shows interferences which we interpret
through a Liouville transformation of the quantum reflection problem
Predicting phase transition pressure in solids: a semiclassical possibility
This is a short review of the physical ideas,algorithm for calculations and
some results of a semiclassical theory of the behaviour of materials under high
pressure,proposed by P.Savic and R.Kasanin.The theory has found applications
from DAC experiments to studies of planetary interior structure.Comment: PDF file,no figure
The Kola Peninsula: Geography, History and Resources
The Kola Peninsula in northwest Russia is one of the most important economic regions in the circumpolar North. The region contains valuable natural resources, including a wide variety of mineral and fish resources, and is proximate to the large gas fields of the Barents Sea. A large population, industrial complexes, and military infrastructure are also characteristic of the region. The Kola Peninsula developed rapidly during the Soviet period (1917-92) under the principles of socialist development policy. This policy favoured extensive resource extraction and industrialization and resulted in increased northern settlement, much of it involuntary. Soviet development policy prompted the opening of new mines and the construction of smelters and refining facilities, while Soviet military policy necessitated the establishment of large military basing operations. Resource development and processing have led to severe environmental damage in the region and beyond. This paper describes the geographical features of the Kola Peninsula and the region's development history and contains data on natural and labour resources.Key words: Kola Peninsula, Murmansk Region, Murmansk, Russian Arctic, Soviet Arctic, natural resources, economic development, militarizationLa presqu'île de Kola dans le nord-ouest de la Russie est l'une des plus importantes zones économiques du Grand Nord circumpolaire. La région contient de précieuses ressources naturelles, y compris une grande variété de ressources minières et de poisson, et elle est proche des champs gaziers de la mer de Barents. Cette région se caractérise aussi par une forte population, ainsi que par la présence de complexes industriels et d'une infrastructure militaire. La presqu'île de Kola s'est développée rapidement au cours de l'ère soviétique (1917-1992), selon les principes des politiques socialistes de développement. Ces dernières, qui mettaient l'accent sur une intensification de l'exploitation des ressources et de l'industrialisation, ont accru la colonisation - en grande partie forcée - dans le Nord. Les politiques soviétiques de développement ont amené l'ouverture de nouvelles mines et la construction de fours de fusion et de raffineries, tandis que les politiques militaires soviétiques ont rendu nécessaire l'édification d'importantes installations pour des bases militaires. L'exploitation et le traitement des ressources ont causé dans la région immédiate et au-delà de sérieux dommages écologiques. Cet article décrit les caractéristiques géographiques de la presqu'île de Kola et l'histoire du développement de la région, et il présente des données sur les ressources naturelles et en main-d'oeuvre.Mots clés : presqu’île de Kola, région de Mourmansk. Mourmansk, Arctique russe, Arctique sovibtique, ressources naturelles, développement économique, militarisatio
Free totally (anti)symmetric massless fermionic fields in d-dimensional anti-de Sitter space
Free massless fermionic fields of arbitrary spins corresponding to
totally (anti)symmetric tensor-spinor representations of the compact
subgroup and in -dimensional anti-de Sitter space are investigated. We
propose the free equations of motion, subsidiary conditions and corresponding
gauge transformations for such fields. The equations obtained are used to
derive the lowest energy values for the above-mentioned representations. A new
representation for equations of motion and gauge transformations in terms of
generators of anti-de Sitter group is found. It is demonstrated
that in contrast to the symmetric case the gauge parameter of the antisymmetric
massless field is also a massless field.Comment: 9 pages, LaTe
Lagrangian Formulation for Free Mixed-Symmetry Bosonic Gauge Fields in (A)dS(d)
Covariant Lagrangian formulation for free bosonic massless fields of
arbitrary mixed-symmetry type in (A)dS(d) space-time is presented. The analysis
is based on the frame-like formulation of higher-spin field dynamics [1] with
higher-spin fields described as p-forms taking values in appropriate modules of
the (A)dS(d). The problem of finding free field action is reduced to the
analysis of an appropriate differential complex, with the derivation Q
associated with the variation of the action. The constructed action exhibits
additional gauge symmetries in the flat limit in agreement with the general
structure of gauge symmetries for mixed-symmetry fields in Minkowski and
(A)dS(d) spaces.Comment: 17 pages, v2: clarifications added, misprints corrected; v3: minor
changes, typos correcte
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