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Radio Emission from Stellar Objects
Published in Ronald L. Snell, Stanley E. Kurtz, Jonathan M. Marr, Fundamentals of Radio Astronomy, 2019
Ronald L. Snell, Stanley E. Kurtz, Jonathan M. Marr
In stars more massive than about 8 M⊙, in their post-main sequence evolution they can fuse heavier and heavier elements, building up an iron core. When this iron core mass exceeds the Chandrasekhar mass Chandrasekhar limit limit of about 1.4 M⊙ (this mass limit is slightly dependent on the composition of the core), the mass of the core can no longer be supported by electron degeneracy pressure and the core collapses catastrophically, leading to a supernova explosion. Supernova For some stars, the remnant core can ultimately be supported by neutron degeneracy pressure, resulting in the formation of a stable neutron star; Neutron star if the mass exceeds the limit for support by neutron degeneracy pressure (a mass between 2 and 3 M⊙), then the collapse results in a black hole. Black hole In this section we discuss neutron stars and their radio frequency emission.
Interaction of ion acoustic solitons for Zakharov Kuznetsov equation in relativistically degenerate quantum magnetoplasmas
Published in Waves in Random and Complex Media, 2021
M. Yousaf Khattak, W. Masood, R. Jahangir, M. Siddiq
According to Pauli's exclusion principle, two electrons can never occupy the same quantum state and so, in the dense plasmas at low temperatures, electrons are distributed according to Fermi-Dirac distribution function and degenerate pressure replaces thermal pressure. In high-density plasmas such as in the core of white dwarfs, Fermi energy of electrons becomes comparable to the rest mass energy of electron and, therefore, on the Fermi surface, electrons move with speed comparable to speed of light in free space. This changes the equation of state for electron degeneracy pressure. Chandrasekhar introduced equation of state for relativistically degenerate electrons in compact astrophysical objects and also gave the nonrelativistic and ultrarelativistic limits [23]. The Chandrasekhar equation of state for nonrelativistic limit is and for ultrarelativistic limit is . As the Chandrasekhar equation of state changes from in nonrelativistic limit to in ultrarelativistic limit, the white dwarf can get gravitationally unstable [24]. This instability brings remarkable changes in the oscillation spectrum of the core of white dwarf and is helpful to investigate the characteristics of star. The above mentioned extreme matter conditions in a celestial body provide us a cosmic laboratory to study the highly dense degenerate state medium (where quantum and relativistic effects are important) as well as the waves propagating through this medium [31–33].