615 research outputs found

    Observed and Physical Properties of Core-Collapse Supernovae

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    I use photometry and spectroscopy data for 24 Type II plateau supernovae to examine their observed and physical properties. This dataset shows that these objects encompass a wide range of ~5 mag in their plateau luminosities, their expansion velocities vary by x5, and the nickel masses produced in these explosions go from 0.0016 to 0.26 Mo. From a subset of 16 objects I find that the explosion energies vary between 0.6x and 5.5x10^51 ergs, the ejected masses encompass the range 14-56 Mo, and the progenitors' radii go from 80 to 600 Ro. Despite this great diversity several regularities emerge, which reveal that there is a continuum in the properties of these objects from the faint, low-energy, nickel-poor SNe 1997D and 1999br, to the bright, high-energy, nickel-rich SN 1992am. This study provides evidence that more massive progenitors produce more energetic explosions, thus suggesting that the outcome of the core collapse is somewhat determined by the envelope mass. I find also that supernovae with greater energies produce more nickel. Similar relationships appear to hold for Type Ib/c supernovae, which suggests that both Type II and Type Ib/c supernovae share the same core physics. When the whole sample of core collapse objects is considered, there is a continous distribution of energies below 8x10^51 ergs. Far above in energy scale and nickel production lies the extreme hypernova 1998bw, the only supernova firmly associated to a GRB.Comment: 25 pages, 7 figures, accepted for Part 1 of Astrophysical Journa

    Mode-coupling and the pygmy dipole resonance in a relativistic two-phonon model

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    A two-phonon version of the relativistic quasiparticle time blocking approximation (RQTBA-2) represents a new class of many-body models for nuclear structure calculations based on the covariant energy density functional. As a fully consistent extension of the relativistic quasiparticle random phase approximation (RQRPA), the two-phonon RQTBA implies a fragmentation of nuclear states over two-quasiparticle and two-phonon configurations. This leads, in particular, to a splitting-out of the lowest 1^- state as a member of the two-phonon [2+3][2^+\otimes3^-] quintuplet from the RQRPA pygmy dipole mode, thus establishing a physical mixing between these three modes. The inclusion of the two-phonon configurations in the model space allows to describe the positions and the reduced transition probabilities of the lowest 1^- states in isotopes 116,120^{116,120}Sn as well as the low-energy fraction of the dipole strength without any adjustment procedures. The model is also applied to the low-lying dipole strength in neutron-rich 68,70,72^{68,70,72}Ni isotopes. Recent experimental data for 68^{68}Ni are reproduced fairly well

    The possibility of administration of glutamate receptors antagonists in the treatment of parkinson's disease

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    Parkinson's disease is the slow-progressing chronic neurodegenerative disease. Modern medicine has not yet found methods of curing disease, however, the existing methods of conservative and surgical treatment significantly improve the patient’s quality of life and slow the progression of the diseas

    R-functions in Development of Analytical Identification of Geometrical Objects

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    In this paper for mathematical and computer modeling of fractal geometry objects, machine parts and building structure the R-functions theory is applied. The mathematical tools of the R-functions theory are very convenient for the fractal geometry objects description. The equations of the Levi fractal, Pythagoras's tree, Koch's curve, cross and snowflake, Menger's sponge (also known as the Menger universal curve), Sierpinski's carpet, etc. have been constructed. The techniques using both the equations of three-dimensional primitives, and information about the equations of boundaries of sections of reset object have been developed. The equations of the automobile body surface, the bearing sleeve, the stepped shaft having two cogged pulleys, the rotary valve, the revolver drum, the screw having the shaped head, cut and lock surface, the cutter lift, the oil filter arm, etc. were constructed. The equations of the hexahedral cartridge having 91 fuel elements have been constructed using only two R-operations

    Optical Photometry of Type II-P Supernova 2004dj in NGC 2403

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    We present photometric data of the type II-P supernova (SN) 2004dj in NGC 2403. The multicolor light curves cover the SN from \sim 60 to 200 days after explosion, and are measured with a set of intermediate-band filters that have the advantage of tracing the strength variations of some spectral features. The light curves show a flat evolution in the middle of the plateau phase, then decline exponentially at the late times, with a rate of 0.10±\pm0.03 mag (10 days)1^{-1} in most of the filters. In the nebular phase, the spectral energy distribution (SED) of SN 2004dj shows a steady increase in the flux near 6600 \AA and 8500 \AA, which may correspond to the emission lines of Hα\alpha and Ca II near-IR triplet, respectively. The photometric behavior suggests that SN 2004dj is a normal SN II-P. Compared with the light curves of another typical SN II-P 1999em, we estimate the explosion date to be June 10±\pm21 UT, 2004 (JD 2453167±\pm21) for SN 2004dj. We also estimate the ejected nickel mass during the explosion to be M(56Ni)M(^{56}\rm{Ni}) = 0.023 ±\pm 0.005 MM_{\odot} from two different methods, which is typical for a SN II-P. We derive the explosion energy E0.750.38+0.56×1051E \approx 0.75^{+0.56}_{-0.38}\times10^{51} erg, the ejecta mass M10.05.2+7.4M \approx 10.0^{+7.4}_{-5.2} MM_{\odot}, and the initial radius R282122+253R \approx 282^{+253}_{-122} RR_{\odot} for the presupernova star of SN 2004dj, which are consistent with other typical SNe II-P.Comment: 15 pages, 9 figures, accepted for publication in A

    Extended Theory of Finite Fermi Systems: Application to the collective and non-collective E1 strength in 208^{208}Pb

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    The Extended Theory of Finite Fermi Systems is based on the conventional Landau-Migdal theory and includes the coupling to the low-lying phonons in a consistent way. The phonons give rise to a fragmentation of the single-particle strength and to a compression of the single-particle spectrum. Both effects are crucial for a quantitative understanding of nuclear structure properties. We demonstrate the effects on the electric dipole states in 208^{208}Pb (which possesses 50% more neutrons then protons) where we calculated the low-lying non-collective spectrum as well as the high-lying collective resonances. Below 8 MeV, where one expects the so called isovector pygmy resonances, we also find a strong admixture of isoscalar strength that comes from the coupling to the high-lying isoscalar electric dipole resonance, which we obtain at about 22 MeV. The transition density of this resonance is very similar to the breathing mode, which we also calculated. We shall show that the extended theory is the correct approach for self-consistent calculations, where one starts with effective Lagrangians and effective Hamiltonians, respectively, if one wishes to describe simultaneously collective and non-collective properties of the nuclear spectrum. In all cases for which experimental data exist the agreement with the present theory results is good.Comment: 21 figures corrected typos in author fiel

    The basic principles of the European state and dynamics of the political and legal development within the Russian Federation

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    The aim of the article is to identify the basic principles of European State and its approval within modern Russia, as well as the specifics of political and legal development of the latter. The methodological basis of research work used the dialectical, phenomenological analysis and synergetic methods to reveal the essence of the basic principles of a European state and the specificity of their adoption in contemporary Russia. The study authors concluded that the implementation of the above principles in practice of political and legal development in Russia is associated with the activity of its civil society, in dialectical interaction with the state.peer-reviewe
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