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1.
A relativistic, first-order differential equation is derived for the accumulated moment of inertia of a spherically symmetric
celestial body. An approximate equation is proposed to describe the contribution of relativistic effects to the moment of
inertia of a superdense star. For configurations of an incompressible fluid, this approximation describes the results of the
numerical calculations of Chandrasekhar and Miller to within 5% in the entire range of central pressures from 0 to ∞.
Translated from Astrofizika, Vol. 40, No. 1, pp. 87–96, January–March, 1997. 相似文献
2.
James B. Hartle 《Astrophysics and Space Science》1973,24(2):385-405
Equations are given which determine the moment of inertia of a rotating relativistic fluid star to second order in the angular
velocity with no other approximation being made. The equations also determine the moment of inertia of matter located between
surfaces of constant density in a rotationally distorted star; for example, the moments of inertia of the crust and core of
a rotationally distorted neutron star can be calculated in this way. The method is applied ton=3/2 relativistic polytropes and to neutron star models constructed from the Baym-Bethe-Pethick-Sutherland-Pandharipande equation
of state.
Supported in part by the National Science Foundation.
Alfred P. Sloan Research Fellow. 相似文献
3.
Armen V. Sarkissian 《Astrophysics and Space Science》1985,117(2):275-286
Rotational stability condition is applied to the PSR 1937+214 pulsar, suggesting that its rapid rotational rate may be close to the limit of rotational stability. This application implies additional bounds on the mass, radius, and moment of inertia of neutron star models, which depend on the theory of gravitation and the equation of state of cold superdense matter. Results obtained for various equations of state and theories of gravitation are used to set limits on the surface magnetic field and slow down rate of pulsar models. 相似文献
4.
A broad sample of computed realistic equations of state of superdense matter with a quark phase transition is used to construct a series of models of neutron stars with a strange quark core. The integral characteristics of the stellar configurations are obtained: gravitational mass, rest mass, radius, relativistic moment of inertia, and red shift from the star's surface, as well as the mass and radius of the quark core within the allowable range of values for the central pressure. The parameters of some of the characteristic configurations of the calculated series are also given and these are studied in detail. It is found that a new additional region of stability for neutron stars with strange quark cores may exist for some models of the equation of state. 相似文献
5.
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
6.
It is shown that knowing the energy flux density of the radio emission, the rate of increase in the period, and the distance
of a pulsar enables one to calculate all the rest of its most important characteristics (the solid angle of the radio emission
beam, the radio luminosity, the solid angle of the beam of γ rays, the energy flux density of the g-ray emission, and the
magnetic moment, moment of inertia, and mass of the neutron star). Equations from which these pulsar characteristics can be
calculated are given at the end of the paper. The results of calculations for a number of pulsars are given in Tables 2 and
3 as an illustration.
Translated from Astrofizika, Vol. 43, No. 2, pp. 277-291, April–June, 2000. 相似文献
7.
A class of well behaved charged superdense star models of embedding class one is obtained by taking perfect fluid to be interior
matter. In the process we come across the models for white dwarf, quark and neutron stars. Maximum mass of the star of this
class is found to be 6.716998M
Θ with its radius is 18.92112 Km. In the absence of charge the models reduce to Schwarzchild’s interior model with constant
density. 相似文献
8.
The dynamics of the vortex lattice in the inner crust of a neutron star is considered. A general equation of motion is obtained
and solved under the assumption that there are regions of pinned and of free vortices. By comparing these solutions with observational
data for the Vela pulsar, the relative moments of inertia of regions of relaxation with the corresponding characteristic times
are calculated for two model stars with different equations of state. It is shown that the theory can be reconciled with observations
of the relaxation of pulsar angular velocity only for model stars with extremely stiff equations of state.
Translated from Astrofizika, Vol. 40, No. 1, pp. 67–76, January–March, 1997. 相似文献
9.
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
10.
11.
G. S. Sahakian 《Astrophysics》2000,43(1):111-126
The theory of pulsar radio emission has been developed in a series of our papers since 1992. It was shown that pulsar radio
emission is produced in the lower part of a channel of open magnetic field lines, in a region with a height h ≈ 1.1-107 μ
30
1/3
/P4/21 cm above a magnetic cap of the neutron star (P is the pulsar’s period and μ is the star’s magnetic moment). Here, owing to
vigorously occurring processes (the production of photons of curvature radiation and their annihilation into e+e- pairs), two ultrarelativistic particle fluxes are formed: an electron flux moving upward and a positron flux falling onto
the star’s magnetic cap. These main fluxes are accompanied by narrow strips of positron and electron fluxes of relatively
low energy, the curvature emission from which is a strong coherent radio source. The present paper is a review of earlier
papers, and important additions and refinements are also made. Equations are offered for the radio luminosity of a pulsar,
the solid angle of the radio beam, and the magnetic moment and moment of inertia of the pulsar’s neutron star.
Translated from Astrofizika, Vol. 43, No. 1, pp. 147-169, January–March, 2000. 相似文献
12.
M. V. Hayrapetyan 《Astrophysics》2008,51(4):559-564
The gravitational radiation of a neutron star with a weakly coupled superfluid component is considered. It is assumed that
regions can exist in the star's core which rotate at substantially higher angular velocities than the observed angular velocities
of pulsars. A star of this sort has a quadrupole moment on the order of the maximum value for the neutron star configurations
that have been discussed, so it could be a powerful source of gravitational radiation for the planned Advanced LIGO detector.
Translated from Astrofizika, Vol. 51, No. 4, pp. 647–652 (November 2008). 相似文献
13.
We investigate the effect of exotic matter in particular, hyperon matter on neutron star properties such as equation of state
(EoS), mass-radius relationship and bulk viscosity. Here we construct equations of state within the framework of a relativistic
field theoretical model. As hyperons are produced abundantly in dense matter, hyperon–hyperon interaction becomes important
and is included in this model. Hyperon–hyperon interaction gives rise to a softer EoS which results in a smaller maximum mass
neutron star compared with the case without the interaction. Next we compute the coefficient of bulk viscosity and the corresponding
damping time scale due to the non-leptonic weak process including Λ hyperons. Further, we investigate the role of the bulk
viscosity on gravitational radiation driven r-mode instability in a neutron star of given mass and temperature and find that
the instability is effectively suppressed.
相似文献
14.
Solutions of the equations of the bimetric scalar—tensor theory of gravitation with a variable scalar field are found for
configurations of superdense matter with different versions of the equation of state. The possible existence of static superdense
and supermassive configurations is established for all of the versions of the equation of state of superdense matter used.
Translated from Astrofizika, Vol. 41, No. 1, pp. 131–135, January-March, 1998. 相似文献
15.
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
16.
D. N. Voskresensky A. V. Senatorov B. Kaempfer H. J. Haubold 《Astrophysics and Space Science》1987,138(2):421-424
It is argued that the neutrino bursts registered on February 23.316 UT, 1987 signalized the transition of a fresh-borne neutron star into a superdense state. The neutron star is supposed to be formed approximately five hours before at February 23.12 UT in the supernova SN 1987a in the Large Magellanic Cloud. 相似文献
17.
J. A. Pons J. F. Pérez-Azorín J. A. Miralles G. Miniutti 《Astrophysics and Space Science》2007,308(1-4):247-257
We propose a self–consistent model to explain all observational properties reported so far on the isolated neutron star (INS)
RX J0720-3125 with the aim of giving a step forward towards our understanding of INSs. For a given magnetic field structure,
which is mostly confined to the crust and outer layers, we obtain theoretical models and spectra which account for the broadband
spectral energy distribution (including the apparent optical excess), the X-ray pulsations, and for the spectral feature seen
in the soft X-ray spectrum of RX J0720-3125 around 0.3 keV. By fitting our models to existing archival X-ray data from 6 different
XMM–Newton observations and available optical data, we show that the observed properties are fully consistent with a normal neutron star, with a proper radius of about 12 km, a temperature at the magnetic pole of about 100 eV, and a magnetic field
strength of 2–3×1013 G. Moreover, we are able to reproduce the observed long–term spectral evolution in terms of free precession which induces
changes in the orientation angles of about 40 degrees with a periodicity of 7 years. In addition to the evidence of internal
toroidal components, we also find strong evidence of non–dipolar magnetic fields, since all spectral properties are better
reproduced with models with strong quadrupolar components.
相似文献
18.
K. Ioka 《Monthly notices of the Royal Astronomical Society》2001,327(2):639-662
We present one possible mechanism for the giant flares of the soft gamma-ray repeaters (SGRs) within the framework of the magnetar (superstrongly magnetized neutron star) model, motivated by the positive period increase associated with the August 27 event from SGR 1900+14. From second-order perturbation analysis of the equilibrium of the magnetic polytrope, we find that there exist different equilibrium states separated by the energy of the giant flares and the shift in the moment of inertia to cause the period increase. This suggests that, if we assume that global reconfiguration of the internal magnetic field of suddenly occurs, the positive period increase as well as the energy ≳1044 erg of the giant flares may be explained. The moment of inertia can increase with a release of energy, because the star shape deformed by the magnetic field can be prolate rather than oblate. In this mechanism, since oscillation of the neutron star will be excited, a ∼ ms-period pulsation of the burst profile and an emission of gravitational waves are expected. The gravitational waves could be detected by planned interferometers such as LIGO, VIRGO and LCGT. 相似文献
19.
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
20.
A. G. Lyne S. L. Shemar F. Graham Smith 《Monthly notices of the Royal Astronomical Society》2000,315(3):534-542
Shemar & Lyne have previously presented observations and an analysis of 32 glitches and their subsequent relaxations observed in a total of 15 pulsars. These data are brought together in this paper with those published by other authors. We show quantitatively how glitch activity decreases linearly with decreasing rate of slow-down. As indicated previously from studies of the Vela pulsar, the analysis suggests that 1.7 per cent of the moment of inertia of a typical neutron star is normally contained in pinned superfluid which releases its excess angular momentum at the time of a glitch. There is a broad range of glitch amplitude and there is a strong indication that pulsars with large magnetic fields suffer many small glitches while others show a smaller number of large glitches. Transient effects following glitches are very marked in young pulsars and decrease linearly with decreasing rate of slow-down, suggesting that the amount of loosely pinned superfluid decreases with age. We suggest that the low braking index of the Vela and Crab pulsars cannot be caused by a decreasing moment of inertia and should be attributed to step increases in the effective magnetic moment of the neutron star at the glitches. 相似文献