3,757 research outputs found
Supernova Ia: a Converging Delayed Detonation Wave
A model of a carbon-oxygen (C--O) presupernova core with an initial mass 1.33
M_\odot, an initial carbon mass fraction 0.27, and with an average mass
growth-rate 5 x 10^{-7} M_\odot/yr due to accretion in a binary system was
evolved from initial central density 10^9 g/cm^3, and temperature 2.05 x 10^8 K
through convective core formation and its subsequent expansion to the carbon
runaway at the center. The only thermonuclear reaction contained in the
equations of evolution and runaway was the carbon burning reaction 12C + 12C
with an energy release corresponding to the full transition of carbon and
oxygen (with the same rate as carbon) into 56Ni. As a parameter we take
\alpha_c - a ratio of a mixing length to the size of the convective zone. In
spite of the crude assumptions, we obtained a pattern of the runaway acceptable
for the supernova theory with the strong dependence of its duration on
\alpha_c. In the variants with large enough values of \alpha_c=4.0 x 10^{-3}
and 3.0 x 10^{-3} the fuel combustion occurred from the very beginning as a
prompt detonation. In the range of 2.0 x 10^{-3} >= \alpha_c >= 3.0 x 10^{-4}
the burning started as a deflagration with excitation of stellar pulsations
with growing amplitude. Eventually, the detonation set in, which was activated
near the surface layers of the presupernova (with m about 1.33 M_\odot) and
penetrated into the star down to the deflagration front. Excitation of model
pulsations and formation of a detonation front are described in detail for the
variant with \alpha_c=1.0 x 10^{-3}.Comment: 13 pages, 11 figures, to appear in Astronomy Letter
Six-loop expansion study of three-dimensional -vector model with cubic anisotropy
The six-loop expansions of the renormalization-group functions of
-vector model with cubic anisotropy are calculated within the minimal
subtraction (MS) scheme in dimensions. The
expansions for the cubic fixed point coordinates, critical exponents
corresponding to the cubic universality class and marginal order parameter
dimensionality separating different regimes of critical behavior are
presented. Since the expansions are divergent numerical estimates
of the quantities of interest are obtained employing proper resummation
techniques. The numbers found are compared with their counterparts obtained
earlier within various field-theoretical approaches and by lattice
calculations. In particular, our analysis of strengthens the existing
arguments in favor of stability of the cubic fixed point in the physical case
Specific features of spin-variable properties of [Fe(acen)pic2]BPh4 · nH2O
© 2016, Pleiades Publishing, Ltd. The [Fe(acen)pic2]BPh4 · nH2O compound has been synthesized and studied in the temperature interval of 5–300 K by the methods of EPR and magnetic susceptibility. The existence of ferromagnetic interactions between Fe(III) complexes in this compound has been revealed, in contrast to unhydrated [Fe(acen)pic2]BPh4. The reduction in the integrated intensity of the magnetic resonance signal as the temperature decreases below 80 K has been explained by the transition of high-spin ions to the low-spin state. It has been shown that the phase transition temperature in the presence of intermolecular (ferromagnetic) interactions is lower than that in the case of noninteracting centers
Results of investigation of muon fluxes of superhigh energy cosmic rays with X-ray emulsion chambers
The overall data from the investigation of the cosmic ray muon flux in the range of zenith angles (0-90) deg within the energy range (3.5 to 5.0) TeV is presented. The exposure of large X-ray emulsion chambers underground was 1200 tons. year. The data were processe using the method which was applied in the experiment Pamir and differred from the earlier applied one. The obtained value of a slope power index of the differential energy spectrum of the global muon flux is =3.7 that corresponds to the slope of the pion generation differential spectrum, gamma sub PI = 2.75 + or - .04. The analysis of the muon zenith-angular distribution showed that the contribution of rapid generation muons in the total muon flux agree the best with the value .2% and less with .7% at a 90% reliability level
Specific features of spin-variable properties of [Fe(acen)pic2]BPh4 · nH2O
© 2016, Pleiades Publishing, Ltd. The [Fe(acen)pic2]BPh4 · nH2O compound has been synthesized and studied in the temperature interval of 5–300 K by the methods of EPR and magnetic susceptibility. The existence of ferromagnetic interactions between Fe(III) complexes in this compound has been revealed, in contrast to unhydrated [Fe(acen)pic2]BPh4. The reduction in the integrated intensity of the magnetic resonance signal as the temperature decreases below 80 K has been explained by the transition of high-spin ions to the low-spin state. It has been shown that the phase transition temperature in the presence of intermolecular (ferromagnetic) interactions is lower than that in the case of noninteracting centers
Lability of spin state of Fe(III) complexes with tetradentate Schiff’s bases
© 2016, Pleiades Publishing, Ltd.[FeLX2]Y [L = N,N'-ethylenebis(salicylimine) (salen), N,N'-ethylenebis(acetylacetonylimine) (acen), or N,N'-ethylenebis(3-methyloxysalicylimine) (vanen); X = imidazole or N-methylimidazole; Y = BF4, ClO4, or BPh4] compounds have been prepared and studied by means of EPR and magnetic susceptibility measurements at 5–300 K. It has been shown that the different electron-donating properties of acen and salen planar ligands result in different spin states of Fe(III) ions. Intermolecular π-interactions of the outer-sphere BPh4 ion affect the complexes spin state as well
On the estimate of the sigma^(I = 1)_(KN)(0)-term value from the energy level shift of kaonic hydrogen in the ground state
Using the experimental data on the energy level shift of kaonic hydrogen in
the ground state (the DEAR Collaboration, Phys. Rev. Lett. 94, 212302 (2005))
and the theoretical value of the energy level shift, calculated within the
phenomenological quantum field theoretic approach to the description of strong
low-energy anti-K N and anti-K NN interactions developed at Stefan Meyer
Institut fuer subatomare Physik in Vienna, we estimate the value of the
sigma^(I = 1)_(KN)(0)-term of low-energy anti-K N scattering. We get sigma^(I =
1)_(KN)(0) = (433 +/- 85) MeV. This testifies the absence of strange quarks in
the proton structure.Comment: 7 pages, no figure
Socio – cultural existence of modern East Mary subethnos
The article deals with the history, traditions and way of life of sub-ethnic group of the Finno-Ugric tribes –the Eastern Maris, who are considered the "last pagans of Europe". Using specific ethnographic material, scientific and popular-scientific works, the authors showed the unique culture of the Eastern Maris sub-ethnos, pagan beliefs, preserved to date and reflecting people’s social existence, beauty of the traditions and essential national characteristics. The authors draw a conclusion that the Eastern Maris present an independent sub-ethnos tending to self-reproduction. Being amidst the powerful Slavic and Turkic civilizations, the Eastern Marian sub ethnos managed to maintain its national self-identity with some borrowings from neighboring cultures
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