共查询到20条相似文献，搜索用时 15 毫秒
1.
假设超新星在坍缩过程中,当物质达到超核密度状态后,在临界密度下发生夸克相交．用ＷＷ（８８）初始模型在有夸克相交情形下对坍缩反弹和激波传播作了模拟,重点讨论了夸克相变对转移能量的影响．在适当的临界密度下发生夸克相交,可以增加转移能量从而得到更强的激波． 相似文献
2.
M. G. Opendak 《Astrophysics and Space Science》1990,165(1):9-25
The Monte-Carlo method has been used to simulate Auger cascades in atoms and ions of Mg, Al, Si, S, Ar, Ca, Fe with account for the radiative and Auger transitions. The probabilities of ejection of various numbers of electrons after the initial creation of vacancy in different shells have been calculated. Corresponding probabilities for atoms and ions of C, N, O, Ne (where single Auger transitions are possible) are presented. The data on radiative and Auger transition rates available in the literature for all the above-mentioned atoms and ions are collected and discussed. 相似文献
3.
Ilya Prigogine 《Astrophysics and Space Science》1979,65(2):371-381
4.
The correlation of subpulse phases across nulls is investigated in the radio pulsar PSR B0031−07, using 29 849 periods of high-quality data obtained with the Ooty Radio Telescope (ORT) which operates at 327 MHz. Assuming that the turn-off and turn-on subpulse phases (the phase of the subpulse in the last period before the null and that in the first period after the null, respectively) are independent random variables, the expected distribution of their difference (i.e. the total drift) is inconsistent with the observed distribution for null transitions within the same drift mode; this implies a correlation of subpulse phase across nulls. However, this correlation decreases with null duration for both the dominant drift modes. Substantial drifting occurs during short nulls (one to four periods); the drift rate during the short nulls appears to be constant for a class A transition, whereas it decreases with null duration for class B transitions. These results, together with the reported behaviour of PSR B1944+17 and PSR B0809+74, seem to imply different time-scales for phase correlation in different pulsars. 相似文献
5.
The possibility that the type of magnetohydrodynamic (MHD) discontinuity changes as the plasma flow conditions gradually change is investigated in a general form. The conservation laws in MHD admit such transitions if there exist the so-called transition solutions that simultaneously satisfy two types of discontinuities. These solutions have been sought for. The system of possible transitions between MHD discontinuities obtained on their basis is presented in a clear schematic form. The ultimate general scheme of transitions includes all of the previously described schemes of transitions known to us. The system of discontinuities and transitions between them is studied in a self-consistent solution of the analytical problem of reconnection in a strong magnetic field. 相似文献
6.
An extensive set of realistic equations of state for superdense matter with a quark phase transition is derived on the basis of the three equations of state for neutron matter and the eight variants of strange quark-gluon plasmas in the MIT quark bag model. The characteristics of the phase transitions are described and the calculated equations of state with a density jump are studied in detail. 相似文献
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The work compiles a correlated study of a gravitational quasi equilibrium thermodynamic approach for establishing and signifying a unique behavior of the cosmological entropy and phase transitions in an expanding Universe. On the basis of prescribed boundary conditions for the cluster temperature a relation for the intra‐cluster medium (ICM) of galaxy clusters has been derived. A more productive and signifying approach of the correlation functions used for galaxy clustering phenomena shows a unique behavior of the entropy change where a phenomenon known as the gravitational phase transition occurs. This unique behavior occurs with a symmetry breaking from mild clustering to low clustering and from mild clustering to high clustering which differs from a normal symmetry breaking in material sciences. We also derive results for the specific latent heat associated with the phase transitions of 3.20 Tc and 0.55 Tc for the mildly clustered phase to the low clustered phase and from the mildly clustered phase to the highly clustered phase, respectively. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
9.
Effects of the phase transitions of superdense matter on supernova explosions are investigated with the aid of an idealized equation of state on the assumptions of adiabatic collapse. It is found that in the case of strong phase transitions explosions become weaker, while in the case of weak phase transitions explosions become stronger. However, the increment of the ejected energy is not so large as suggested by Migdalet al. (1979).Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
10.
Transition probabilities for some excited s-p and p-s transition arrays of neutral nitrogen have been calculated using the weakest bound electron potential model theory (WBEPMT) for the investigation of effects of expectation values of radii.We have used both numerical non-relativistic Hartree-Fock (NRHF) wave functions and numerical Coulomb approximation (NCA) wave functions to calculate expectation values of radii. The transition probability results obtained using the parameters determined with two different wave functions agree well with each other and accepted values taken from NIST for low values of transition probability. However, the NRHF wave functions present better results for p-s transitions, while NCA wave functions are better in s-p transitions for large values of transition probability. 相似文献
11.
The first order deconfinement phase transitions in rotating hybrid stars are studied and it is found that if the surface tension is sufficiently large, the transition from metastable hadron matter to stable mixed hadron-quark matter during the spindown history of a hybrid star can cause a glitch. 相似文献
12.
William R. Tavares Rodrigo M. Nunes Sidney S. Avancini Ricardo L. S. Farias 《Astronomische Nachrichten》2024,345(2-3):e230168
The Nambu–Jona-Lasinio model is known for its simplicity and capacity to reproduce some of the basic characteristics of the quantum chromodynamics phase diagram. However, since it is a nonrenormalizable model, there are regularization issues that should be treated conveniently. This is the case when considering the quark anomalous magnetic moment (AMM) when external constant magnetic fields are present. Regularization procedures based on entangled functions between the magnetic field and the cutoff of the model can predict first-order phase transitions for chiral symmetry restoration at finite values of magnetic fields and inverse magnetic catalysis. The strengths of magnetic fields explored in NJL model and lattice QCD do not show first-order phase transition. In the present work, we show that some of the previous results are regularization-dependent effects and how to handle the divergences using the vacuum magnetic regularization scheme. 相似文献
13.
Vladan čelebonović 《Earth, Moon, and Planets》1989,45(3):291-298
When subject to high pressure, H2 and 3He are expected to undergo phase transitions, and to become metallic at a sufficiently high pressure. Using a semiclassical theory of dense matter proposed by Savi and Kaanin, calculations of phase transition and metallisation pressure have been performed for these two materials. In hydrogen, metallisation occurs at p
M= (3.0 ± 0.2) Mbar, while for helium the corresponding value is p
M= (106 ± 1) Mbar. A phase transition occurs in helium at p
tr= (10.0 ± 0.4) Mbar. These values are close to the results obtainable by more rigorous methods. Possibilities of experimental verification of the calculations are briefly discussed. 相似文献
14.
We study possible impact of a softening of the equation of state by a phase transition, or appearance of hyperons, on the
spin evolution of isolated pulsars. Numerical simulations are performed using exact 2-D simulations in general relativity.
The equation of state of dense matter at supranuclear densities is poorly known. Therefore, the accent is put on the general
correlations between evolution and equation of state, and mathematical strictness. General conjectures referring to the structure
of the one-parameter families of stationary configurations are formulated. The interplay of the back bending phenomenon and
stability with respect to axisymmetric perturbations is described. Changes of pulsar parameters in a corequake following instability
are discussed, for a broad choice of phase transitions predicted by different theories of dense matter. The energy release
in a corequake, at a given initial pressure, is shown to be independent of the angular momentum of collapsing configuration.
This result holds for various types of phases transition, with and without metastability. We critically review observations
of pulsars that could be relevant for the detection of the signatures of the phase transition in neutron star cores.
This work was partially supported by the Polish MNiI Grant no. 1P03D-008-27. 相似文献
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The properties of adiabatic potential transitions in a current carrying plasma are investigated and classified. It is shown that it is important to include pressure effects since the character of the transition (e.g. whether or not it behaves as a particle accelerator) is determined by whether the speed of a streaming species on entering the transition is less or greater than the “sound speed” of that species. If electrons are the main current carriers in the field aligned current systems associated with the polar ionosphere and magnetosphere we find that, under typical conditions, their drift speed is less than their thermal speed with the implication that if they enter a potential transition their pressure gradient will overcome the electrostatic field so that they are decelerated and heated by the transition. Under disturbed conditions when the field aligned current densities are exceptionally high, potential transitions act as particle accelerators. 相似文献
17.
Exact formulas are derived for calculating the correction for phase to the central meridian longitude and the latitude of the center of the illuminated part of the visible disk of a spherical planet in projection onto the plane of the sky. The range of possible values of the phase correction to the central meridian longitude is determined. The proposed formulas are valid for any planet's orientation with respect to the Earth and Sun and allow a transition, in planetocentric coordinates, from the center of the geometric disk of a spherical planet to the center of the illuminated part of the planet's visible disk. The reduction formulas are derived for direct and inverse transitions between the two aforementioned points of the planetary disk in geocentric equatorial coordinates. The examples of special cases of illumination of visible disks of planets in specific ephemeris are given. 相似文献
18.
Emission line spectra observed at the limb of the solar disc are presented for transitions of singly ionized silicon at 1816.93, 1817.45 and 1808.01. The profiles show self-reversals in the line cores. A non-LTE analysis for a simplified model of the silicon ion is presented and calculated line profiles are compared with the observations. The study indicates that some modification of the Vernazza et al. (1973) model of the solar chromosphere in the transition region is needed to reconcile the calculated and observed profiles. 相似文献
19.
S. O. Kastner 《Solar physics》1976,46(1):179-182
Forbidden transition probabilities are listed for ground term transitions of ions in the B I. F I, Al I and Cl I sequences. Some of these transitions remain to be observed in flares. 相似文献
20.
M. Velli 《Astrophysics and Space Science》2001,277(1-2):157-167
A pedagogical introduction to the classical hydrodynamic steady state solutions for flows in a spherically symmetric atmosphere is presented along with a detailed analysis of the stability of such flows and a discussion of the Parker/Bondi phase diagram of solutions in the Mach number – stellar radius plane. This leads naturally to the scenario presented by Velli (1994) for wind-accretion transitions, which helps to explain results from numerical simulations in many contexts and gives a more comprehensive answer to the question of why the solar wind and other steady state flows in spherical symetry must quite generally become supersonic. 相似文献