The Study of the Highly Compact Stellar Structure

• Main Authors: Lu, Jing-Yu, 盧勁羽
• Other Authors: Choon-Lin Ho
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/42186699928365055001

碩士 === 淡江大學 === 物理學系 === 85 === In this thesis we first discuss three fundamental aspects of compact stars: the hydrostatic equilibrium, polytropes and Lane- Emden equation. The idea of polytropes first originated from the works of Lord Kelvin. Combining the equation of hydrostatic equilibrium and polytropes, we obtain the Lane-Emden equation. White dwarfs are considered as spherical distributed ideal gas of highly degenerate electrons. In both the non-relativistic limits and the highly relat-ivistic limits, the white dwarfs are polytropes. So we can use the Lane-Emden equation. In the highly relativistic limits we obtain the mass limit of the white dwarfs, which is 1.4 times the solar mass. This limit is called the Chandrasekhar limit. By the same consideration, we can compute the mass limit of the neutron star, which is 5.69 times the solar mass. For large mass and high density, we must take into account the effect of the general relativity. According to the Oppenheimer-Volkoff's ideal neutr- on gas model, the limiting mass is found to be 0.7 times the solar mass. In fact, an actual neutron star will have different layers of structures: the surface ( composing of irons ), the out crust ( composing of the heavy nucl- ei and electrons ), the inner crust ( composing of the neutron-rich nuclei and neutrons ), the neutron liquid and the core. Up to now the core's struct- ure is uncertain. For the core we may have several possibilities: the neutron solid, the hyperon liquid, ( condensation and the quark matter. In the last chapter we consider the chemical equilibrium of the neutron star, assumed to be composed almost entirely of neutrons and little amount of protons and electrons. The maximum of proton-neutron ratio is 1/8.