scholarly journals Binary and ternary ionic compounds in the outer crust of a cold nonaccreting neutron star

2016 ◽  
Vol 94 (6) ◽  
Author(s):  
N. Chamel ◽  
A. F. Fantina
Keyword(s):  
Neutron Star ◽  
Ionic Compounds ◽  
Outer Crust

scholarly journals Neutron stars from crust to core within the Quark-meson coupling model

2020 ◽  
Vol 232 ◽  
pp. 03001
Author(s):  
S. Antić ◽  
J. R. Stone ◽  
A. W. Thomas
Keyword(s):  
Neutron Star ◽  
Dense Matter ◽  
Building Blocks ◽  
Coupling Model ◽  
Meson Coupling ◽  
Exciting Time ◽  
Cold Dense Matter ◽  
Finite Nuclei ◽  
Outer Crust

Recent years continue to be an exciting time for the neutron star physics, providing many new observations and insights to these natural ‘laboratories’ of cold dense matter. To describe them, there are many models on the market but still none that would reproduce all observed and experimental data. The quark-meson coupling model stands out with its natural inclusion of hyperons as dense matter building blocks, and fewer parameters necessary to obtain the nuclear matter equation of state. The latest advances of the QMC model and its application to the neutron star physics will be presented, within which we build the neutron star’s outer crust from finite nuclei up to the neutron drip line. The appearance of different elements and their position in the crust of a neutron star is explored and compared to the predictions of various models, giving the same quality of the results for the QMC model as for the models when the nucleon structure is not taken into account.

scholarly journals Impact of statistical uncertainties on the composition of the outer crust of a neutron star

2020 ◽  
Vol 101 (3) ◽  
Author(s):  
A. Pastore ◽  
D. Neill ◽  
H. Powell ◽  
K. Medler ◽  
C. Barton
Keyword(s):  
Neutron Star ◽  
Outer Crust

scholarly journals Effects of Superfluidity on Spheroidal Oscillations of Neutron Stars

1994 ◽  
Vol 147 ◽  
pp. 586-590
Author(s):  
Umin Lee ◽  
T.J.B. Collins ◽  
H.M. Van Horn ◽  
R.I. Epstein
Keyword(s):  
Wave Propagation ◽  
Neutron Star ◽  
Neutron Stars ◽  
Short Wavelength ◽  
Surface Gravity ◽  
Frequency Spectra ◽  
Global Oscillation ◽  
Oscillation Modes ◽  
Outer Crust ◽  
Spheroidal Oscillations

AbstractIn the limit of short wavelengths, it has been shown that superfluidity significantly affects wave propagation in neutron stars. Here we abandon the short-wavelength restriction and extend these calculations to global oscillation modes. In the present analysis, the solid crust of the neutron star is divided into an outer crust and an inner crust, and a superfluid of neutrons coexists with the solid lattice in the inner crust. We have computed several low-order global spheroidal modes for l = 2 both with and without superfluidity. We find that superfluidity in the inner crust affects the frequency spectra of acoustic (p-) modes, shear (s-) modes, and interfacial (i-) modes, although the surface gravity (g-) modes are not affected at all.

scholarly journals Crystallization of the outer crust of a non-accreting neutron star

2020 ◽  
Vol 633 ◽  
pp. A149 ◽  
Author(s):  
A. F. Fantina ◽  
S. De Ridder ◽  
N. Chamel ◽  
F. Gulminelli
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Coupling Parameter ◽  
Equilibrium Composition ◽  
Nuclear Model ◽  
Self Consistent ◽  
Component Plasma ◽  
Rotational Evolution ◽  
The One ◽  
Outer Crust

Context. The interior of a neutron star is usually assumed to be made of cold catalyzed matter. However, the outer layers are unlikely to remain in full thermodynamic equilibrium during the formation of the star and its subsequent cooling, especially after crystallization occurs. Aims. We study the cooling and the equilibrium composition of the outer layers of a non-accreting neutron star down to crystallization. Here the impurity parameter, generally taken as a free parameter in cooling simulations, is calculated self-consistently using a microscopic nuclear model for which a unified equation of state has recently been determined. Methods. We follow the evolution of the nuclear distributions of the multi-component Coulomb liquid plasma fully self-consistently, adapting a general formalism originally developed for the description of supernova cores. We calculate the impurity parameter at the crystallization temperature as determined in the one-component plasma approximation. Results. Our analysis shows that the sharp changes in composition obtained in the one-component plasma approximation are smoothed out when a full nuclear distribution is allowed. The Coulomb coupling parameter at melting is found to be reasonably close to the canonical value of 175, except for specific values of the pressure for which supercooling occurs in the one-component plasma approximation. Our multi-component treatment leads to non-monotonic variations of the impurity parameter with pressure. Its values can change by several orders of magnitude reaching about 50, suggesting that the crust may be composed of an alternation of pure (highly conductive) and impure (highly resistive) layers. The results presented here complement the recent unified equation of state obtained within the same nuclear model. Conclusions. Our self-consistent approach to hot dense multi-component plasma shows that the presence of impurities in the outer crust of a neutron star is non-negligible and may have a sizeable impact on transport properties. In turn, this may have important implications not only for the cooling of neutron stars, but also for their magneto-rotational evolution.

scholarly journals Crystallization of the inner crust of a neutron star and the influence of shell effects

2020 ◽  
Vol 635 ◽  
pp. A84 ◽  
Author(s):  
T. Carreau ◽  
F. Gulminelli ◽  
N. Chamel ◽  
A. F. Fantina ◽  
J. M. Pearson
Keyword(s):  
Neutron Star ◽  
Finite Temperature ◽  
Nuclear Reactions ◽  
Compressible Liquid ◽  
Quantitative Prediction ◽  
Particle Structure ◽  
Shell Effects ◽  
Component Plasma ◽  
The One ◽  
Outer Crust

Context. In the cooling process of a non-accreting neutron star, the composition and properties of the crust are thought to be fixed at the finite temperature where nuclear reactions fall out of equilibrium. A lower estimate for this temperature is given by the crystallization temperature, which can be as high as ≈7 × 109 K in the inner crust, potentially leading to sizeable differences with respect to the simplifying cold-catalyzed matter hypothesis. Aims. We extend a recent work on the outer crust to the study of the crystallization of the inner crust and the associated composition in the one-component plasma approximation. Methods. The finite temperature variational equations for non-uniform matter in both the liquid and the solid phases are solved using a compressible liquid-drop approach with parameters optimized on four different microscopic models that cover current uncertainties in nuclear modeling. Results. We consider the effect of the different nuclear ingredients with their associated uncertainties separately: the nuclear equation of state, the surface properties in the presence of a uniform gas of dripped neutrons, and the proton shell effects arising from the ion single-particle structure. Our results suggest that the highest source of model dependence comes from the smooth part of the nuclear functional. Conclusions. We show that shell effects play an important role at the lowest densities close to the outer crust, but the most important physical ingredient to be settled for a quantitative prediction of the inner crust properties is the surface tension at extreme isospin values.

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