共查询到20条相似文献，搜索用时 15 毫秒
1.
2.
Huan-yu Jia Bao-xi Sun Jie Meng En-guang Zhao 《Chinese Astronomy and Astrophysics》2002,26(4):901-413
Neutron stars are studied in the framework of the relativistic mean field theory of interacting nucleons, hyperons, and mesons. Within the hadronic freedom, the cores of neutron stars are found to be dominated by hyperons when the density is sufficiently high. The influence of hyperon coupling constants on the transition from a neutron star to a hyperon-dominated strange neutron star is also investigated. It is found that the transition density gets its minimum value when the ratio of hyperon coupling constant to nucleon's takes the value of 0.65, and the calculated maximum mass of the neutron star is 1.4 M which lies within the range of the observational results. 相似文献
3.
Mass, radius and moment of inertia are direct probes of compositions and Equation of State (EoS) of dense matter in neutron star interior. These are computed for novel phases of dense matter involving hyperons and antikaon condensate and their observable consequences are discussed in this article. Furthermore, the relationship between moment of inertia and quadrupole moment is also explored. 相似文献
4.
G. F. Burgio M. Baldo O. E. Nicotra H.-J. Schulze 《Astrophysics and Space Science》2007,308(1-4):387-394
We study the structure of protoneutron stars within the finite-temperature Brueckner–Bethe–Goldstone many-body theory. If
nucleons, hyperons, and leptons are present in the stellar core, we find that neutrino trapping stiffens considerably the
equation of state, because hyperon onsets are shifted to larger baryon density. However, the value of the critical mass turns
out to be smaller than the “canonical” value 1.44M
⊙. We find that the inclusion of a hadron-quark phase transition increases the critical mass and stabilizes it at about 1.5–1.6M
⊙.
相似文献
5.
In part I we suggested an approximate equation to determine the contribution of relativistic effects to the moment of inertia
of a superdense star. In the present paper it is tested on model neutron stars with nine different variants of the equation
of state of superdense matter. It is established that the approximation error does not exceed 5% for stable configurations.
A more accurate version of the Ravenhall—Pethick equation [D. G. Ravenhall and C. J. Pethick, Astrophys. J., 424, 846 (1994)]
for the moment of inertia as a function of the mass and radius of a neutron star is derived.
Translated from Astrofizika, Vol. 40, No. 4, pp. 507–516, October–December, 1997. 相似文献
6.
N. Andersson 《Astrophysics and Space Science》2007,308(1-4):395-402
In this brief summary I describe our recent work on superfluid neutron star dynamics. I review results on shear viscosity,
hyperon bulk viscosity, vortex mediated mutual friction and the modelling of multifluid systems in general. For each problem
I provide a set of questions that need to be addressed by future work. 相似文献
7.
B. Kmpfer 《Astronomische Nachrichten》1984,305(4):193-197
We derive an upper bound on neutron star masses by using model equations of state in the nuclear matter density region and the causality limited equation of state in the ultradense region. Supposing that the model equations of state describe neutron star matter at nuclear matter density correctly we find as bound 3.75 M⊙. For large fiducial densities one gets a maximum mass which is above a previous estimate. 相似文献
8.
S. Schramm V. Dexheimer A. Mukherjee J. Steinheimer 《Journal of Astrophysics and Astronomy》2018,39(4):42
The interior of neutron stars consists of the densest, although relatively cold, matter known in the universe. Here, baryon number densities might reach values close to ten times the nuclear saturation density. These suggest that the constituents of neutron star cores not only consist of nucleons, but also of more exotic baryons like hyperons or a phase of deconfined quarks. We discuss the consequences of such exotic particles on the gross properties and phenomenology of neutron stars. In addition, we determine the general phase structure of dense and also hot matter in the chiral parity-doublet model and confront model results with the recent constraints derived from the neutron star merger observation. 相似文献
9.
S. Campana M. Colpi S. Mereghetti L. Stella M. Tavani 《Astronomy and Astrophysics Review》1998,8(4):279-316
Summary. Soft X–ray Transients (SXRTs) have long been suspected to contain old, weakly magnetic neutron stars that have been spun
up by accretion torques. After reviewing their observational properties, we analyse the different regimes that likely characterise
the neutron stars in these systems across the very large range of mass inflow rates, from the peak of the outbursts to the
quiescent emission. While it is clear that close to the outburst maxima accretion onto the neutron star surface takes place,
as the mass inflow rate decreases, accretion might stop at the magnetospheric boundary because of the centrifugal barrier
provided by the neutron star. For low enough mass inflow rates (and sufficiently short rotation periods), the radio pulsar
mechanism might turn on and sweep the inflowing matter away. The origin of the quiescent emission, observed in a number of
SXRTs at a level of , plays a crucial role in constraining the neutron star magnetic field and spin period. Accretion onto the neutron star surface
is an unlikely mechanism for the quiescent emission of SXRTs, as it requires very low magnetic fields and/or long spin periods.
Thermal radiation from a cooling neutron star surface in between the outbursts can be ruled out as the only cause of the quiescent
emission.
We find that accretion onto the neutron star magnetosphere and shock emission powered by an enshrouded radio pulsar provide
far more plausible models. In the latter case the range of allowed neutron star spin periods and magnetic fields is consistent
with the values recently inferred from the properties of kHz quasi-periodic oscillation in low mass X–ray binaries. If quiescent
SXRTs contain enshrouded radio pulsars, they provide a missing link between X–ray binaries and millisecond pulsars.
Received 4 November 1997; Accepted 15 April 1998 相似文献
10.
The constraints on the properties of neutron star matter from the mass of neutron star PSR J1614-2230 are examined in the framework of the relativistic mean field theory. We find that there are little differences between the σ potentials of large mass neutron star and those of canonnical mass neutron star. For potentials of ω, ρ, neutrons and electrons, the values corresponding to the large mass neutron star are larger than those to the canonnical mass neutron star as the baryon number density is more than a certain value. We also find that for the relative particle number density of electrons, muons, neutrons and protons and the pressure of the neutron star, the values corresponding to the large mass neutron star are far larger than those to the canonnical mass neutron star. For the relative particle number density of hyperons Λ, Σ?, Σ0, Σ+ and Ξ?, the values corresponding to the large mass neutron star are far smaller than those to the canonnical mass neutron star. These mean that the larger mass of neutron star is more advantageous to the production of protons but is not advantageous to the production of hyperons. 相似文献
11.
Evolutionary calculations based on realistic equations of state indicate the stratified nature of the distribution of hadron
matter in the interiors of neutron stars. In the proposed model, the stratified structure of a neutron star is treated as
a rigid inert core surrounded by a dynamical layer. The physical basis for the model is the concept of the stellar matter
of the peripheral envelope as an elastic Fermi continuum, the motions of which are described by the equations of nuclear elastodynamics,
proposed in the macroscopic theory of collective processes in laboratory nuclear physics. It is shown that the vibrational
dynamics of a neutron star is characterized by two branches of gravitational—elastic, spheroidal (s-mode) and torsional (t-mode)
nonradial eigenvibrations. Estimates obtained for the periods of global, gravitational nonradial modes suggest that variations
in the intensity of micropulses observed in the millisecond range of the spectra of C-pulsars may be ascribed to these vibrations.
The proposed two-component model of a neutron star enables one to consider a glitch in a pulsar’s radio emission as a starquake
due to the passage of the companion through periastron of the binary system.
Translated from Astrofizika, Vol. 42, No. 2, pp. 235–252, April–June, 1999 相似文献
12.
James M. Lattimer 《Astrophysics and Space Science》2007,308(1-4):371-379
Recent measurements of thermal radiation from neutron stars have suggested a rather broad range of radiation radii (
). Sources in M13 and Omega Cen imply R
∞∼12–14 km, but X7 in 47 Tuc implies R
∞∼16–20 km and RX J1856-3754 R
∞>17 km. If these measurements are all correct, only a limited selection of EOS’s could be consistent with them, but a broad
range of neutron star masses (up to 2 M⊙) would also be necessary. The surviving equations of state are incompatible with significant softening above nuclear saturation
densities, such as would occur with Boson condensates, a low-density quark-hadron transition, or hyperons. Other potential
constraints, such as from QPO’s, radio pulsar mass and moment of inertia measurements, and neutron star cooling, are compared.
US DOE Grant DE-FG02-87ER-40317. 相似文献
13.
14.
Qi Zhan-qiang Ding Wen-bo Zhang Cheng-min Hou Jia-wei 《Chinese Astronomy and Astrophysics》2018,42(1):69-80
By the relativistic mean field theory and relevant weak-interactional cooling theory, the relativistic cooling properties in the conventional and hyperonic neutron star matter are studied. Also a comparison between the relativistic and non-relativistic results after taking consideration of the gravity correction is performed. The results show that the relativistic effect of neutrino emission reduces the neutrino emissivity, luminosity, and the cooling rate of stellar objects, in comparison with the non-relativistic case. In the neutron star matter without hyperon, the amplitude of the cooling rate reduction caused by the relativistic effect is maximal after taking the gravity correction into consideration, it attains 56% for a 2 M⊙ neutron star composed of conventional neutron star matter, and in the hyperonic matter the amplitude of reduction is minimal, about 38%. 相似文献
15.
In our preceding paper we found solutions for the equations of the bimetric scalar—tensor theory of gravitation for neutron
stars, in which the scalar field is constant while the metric tensor satisfies the equations of the general theory of relativity.
In the present paper we find analogous solutions for different versions of the equation of state of the matter of a neutron
star.
Translated from Astrofizika, Vol. 41, No. 2, pp. 297–301. April-June, 1998. 相似文献
16.
《天文和天体物理学研究(英文版)》2015,(6)
Using a realistic equation of state(EOS) of strange quark matter, namely,the modified bag model, and considering the constraints on the parameters of EOS by the observational mass limit of neutron stars, we investigate the r-mode instability window of strange stars, and find the same result as in the brief study of Haskell,Degenaar and Ho in 2012 that these instability windows are not consistent with the spin frequency and temperature observations of neutron stars in low mass X-ray binaries. 相似文献
17.
We investigate the instability driven by viscosity in rotating relativistic stars by means of an iterative approach. We focus
on polytropic rotating equilibrium stars and impose an m=2 perturbation in the lapse. We vary both the stiffness of the equation of state and the compactness of the star to study
these factors on the critical value T/W for the instability. For a rigidly rotating star, the criterion T/W, where T is the rotational kinetic energy and W the gravitational binding energy, mainly depends on the compactness of the star and takes values around 0.13–0.16, which
slightly differ from that of Newtonian incompressible stars (∼0.14). For differentially rotating stars, the critical value
of T/W is found to span the range 0.17–0.25. The value is significantly larger than in the rigidly rotating case with the same compactness
of the star. Finally we discuss the possibility of detecting gravitational waves from viscosity-driven instabilities using
ground-based interferometers.
相似文献
18.
We have considered a hot neutron star with a quark core,a mixed phase of quark-hadron matter,and a hadronic matter crust and have determined the equation of state of the hadronic phase and the quark phase.We have then found the equation of state of the mixed phase under the Gibbs conditions.Finally,we have computed the structure of a hot neutron star with a quark core and compared our results with those of the neutron star without a quark core.For the quark matter calculations,we have used the MIT bag model... 相似文献
19.
《Chinese Astronomy and Astrophysics》2005,29(1):53-60
Taking into account the peculiar properties of hybrid stars, stars containing both a core of strange quark matter and the solid crust of a neutron star, and employing a fully self-consistent second-order correction technique, we study the time scale of bulk viscosity dissipation at the low temperature limit (T < 109 K) and with this time scale we calculate the critical spin frequency of the hybrid star. It is found that its minimal value is 704.42 Hz (corresponding to a pulse period of 1.42 ms). When this is compared with the periods of neutron and strange stars, a better interpretation of the observational data is obtained. 相似文献
20.
We present results from simulations of protoneutron star thermal evolution using neutrino opacities that are consistently
calculated with the equation of state. When hyperons are allowed to appear in the system, we obtain metastable configurations
that after the deleptonization stage become unstable. Concerning the evolution of old neutron stars, we present the results
of our investigation on the effect of the Joule heating due to magnetic field dissipation. We conclude that this mechanism
can be efficient in maintaining the surface temperature of the star above 3 × 104 - 105 K during a very long time (≥ 100 Myr), comparable with the decay time of the magnetic field.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献