Neutron stars rotation

Neutron stars rotate rapidly. This is because the original stellar core was rotating, and as it collapsed its rotation rate increased, in the same way figure skaters spin increasingly rapidly by drawing their extended arms in to their sides. 

Many neutron stars look like the drawing in Figure 1. The neutron star s rotation axis is inclined with respect to its magnetic axis. (The same situation prevails on Earth.) The neutron star s rapid rotation and intense magnetic field cause radiation to be emitted in narrow beams from the magnetic poles. If the Earth happens to be in line with one of these beams, we will see a flash every time the neutron star rotates and carries the beam past us. 

The problem of rotation of neutron stars in the framework of General Relativity Theory was solved before the discovery of pulsars and the important contribution of the Armenian scientists in this work is well documented. With all... 

The commonly accepted pulsar model is a neutron star of about one solar mass and a radius of the order of ten kilometers. A neutron star consists of a crust, which is about 1 km thick, and a high-density core. In the crust free neutrons and electrons coexist with a lattice of nuclei. The star s core consists mainly of neutrons and a few percents of protons and electrons. The central part of the core may contain some exotic states of matter, such as quark matter or a pion condensate. Inner parts of a neutron star cool up to temperatures 108iT in a few days after the star is formed. These temperatures are less than the critical temperatures Tc for the superfluid phase transitions of neutrons and protons. Thus, the neutrons in the star s crust and the core from a superfluid, while the protons in the core form a superconductor. The rotation of a neutron superfluid is achieved by means of an array of quantized vortices, each carrying a quantum of vorticity... 

In section I we consider the dynamics of rotation of a two-component neutron star and obtain the relaxation solutions for spin-down rate of the star. In section II we compare our solutions for the relaxation process with the observation data from the Vela pulsar. 

Let us consider the rotational dynamics of a two-component neutron star taking into account the pinning and depinning of neutron vortices. Equations of motion of the superfluid and normal components have the following forms [15, 17] ... 

Zavlin, V.E., Pavlov, G.G., Shibanov, Y.A., Ventura, J. (1995), Thermal radiation from rotating neutron star effect of the magnetic field and surface temperature distribution , A A 297, 441. 

Abstract The behavior of the magnetic field of a rotating neutron star with a superconduct-... 

Figure 4 The annihilation of neutrino-antineutrino pairs above the remnant of a neutron star merger drives relativistic jets along the original binary rotation axis (only upper half-plane is shown). The x-axis lies in the original binary orbital plane, the dark oval around the origin is the newly formed, probably unstable, supermassive neutron star formed in the coalescence. Color-coded is the asymptotic Lorentz-factor. Details can be found in Rosswog et al. 2003.

The neutron star formed after the merger may be supported by rapid and differential rotation even if its mass exceeds 60% of the maximum mass of a single non-rotating neutron star, and the GWs are emitted due to non-axisymmetric andquasiradial oscillations of the remnant for longer than the dynamical timescale [30], If these oscillations persist for a longer time, the integrated GW may be... 

Exceptionally violent phenomena can nevertheless disturb this fine order. Some of them bring tremendous speeds into play, in both translational and rotational motions. Solar and stellar flares come to mind, along with exploding stars and spinning pulsars (neutron stars). If part of this well-ordered energy is conferred upon an atomic nucleus, it then becomes a cosmic ray. It is thus excluded from the community, whose gentle brethren are no longer able to retain it. 

SUMMARY We investigate the unsteady motion of mass reservoir formed by the accretion onto the magnetosphere around rotating neutron stars. The unsteady motion of the reservoir induces secondary accretion to neutron star by R-T instability. The nonperiodic or quasiperiodic phenomena of X-ray bursters seems to be related to this property of mass reservoir on the magnetosphere. We classify the typical dynamical state of the reservoir into three types with the parameters which are accretion rate M and angular velocity of neutron star ft. They are nonsequential oscillation sequential periodic (quasi-periodic) oscillation, and chaotic oscillation states. 

We assume that the stellar magnetic field is dipolar ( m d), and has axial symmetry everywhere. We use cylindrical coordinates (w,, z) centered on the neutron star and aligned with the stellar rotation axis. This configuration is sketched in Figure 1. We obtain the nondimensionalized equations which construct a complete set for the dynamics of reservoir ring, as following,... 

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