Publication Abstracts

Chiu 1964

Chiu, H.-Y, 1964: Supernovae, neutrinos, and neutron stars. Ann. Phys., 26, no. 3, 364-410, doi:10.1016/0003-4916(64)90256-8.

In this paper the final stage of stellar evolution is studied from a theoretical point of view. Two types of stellar instabilities (hydrostatic instability and dynamical instability) are studied. It is concluded that at a temperature of T ∼ 6×109 °K, both hydrostatic instability, which is induced by the photodisintegration of iron into helium (phase change), and dynamical instability, which is induced by the annihilation process of neutrino production, can cause a star to collapse to beyond recovery. Moreover, neutrino processes involving electron-neutrinos and μ-neutrinos prohibit any temperature rise in the star during the collapse phase. Hence the collapse will take place under zero temperature conditions (kT ⪡ Fermi energy of electrons).

The structure of static, zero temperature stars is reviewed. When the density is less than 108 gm/cm3 the star is composed of ordinary ionized nuclei. When the mass approaches 1.4 M (M = solar mass = 2×1033 gm) the density reaches a value that the electron zero point energy (Fermi energy) exceeds the energy difference between isobars. Inverse beta reactions then take place, decreasing the number of electrons, causing instability (hydrostatic instability). Because of this instability, no star exists whose density ranges from 109 to 1013 gm/cm3.

After a density of 1013 gm/cm3 is reached, inverse beta reactions have eliminated all but a very small number of electrons. No nuclei can exist and the star is predominantly made of neutrons (neutron stars). Such a high concentration of mass produces a large curvature of space-time near the star. General relativity theory is used to describe the structure of such stars.

General relativity theory predicts the existence of singularities. Two kinds of gravitational singularities may exist, according to a static, general relativistic description of cold stars. One kind of singularity corresponds to a classical situation that, at the center of such a star the gravitational potential of a test body is equal to its rest energy. Hence matter "disappears" through this kind of singularity. The other singularity corresponds to the same situation except the whole star "cuts itself off" from the rest of the universe by producing a large curvature near the star such that not even photons may leave it.

However, it is indicated by work done in the past that a static description is probably unrealistic. Even in a gedanken sense, slowly adding material to a star will inevitably cause it to collapse dynamically. No completely satisfactory solution for a dynamically collapsing star has been found.

The fate of collapsing massive stars (which are believed to be related to supernovae which occur at a rate of around one per hundred years per galaxy) is hence unknown, even in a theoretical sense.

The surface of the remains of such stars, if visible at all, will have a temperature of around 106 °K-107 °K. Most of the radiation from such stars will be in the x-ray band and will not penetrate through our atmosphere. Hence, for the detection of such stars an orbiting telescope working in the near x-ray band will be most useful.

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BibTeX Citation

  author={Chiu, H.-Y},
  title={Supernovae, neutrinos, and neutron stars},
  journal={Annals of Physics},

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RIS Citation

ID  - ch01510v
AU  - Chiu, H.-Y
PY  - 1964
TI  - Supernovae, neutrinos, and neutron stars
JA  - Ann. Phys.
JO  - Annals of Physics
VL  - 26
IS  - 3
SP  - 364
EP  - 410
DO  - 10.1016/0003-4916(64)90256-8
ER  -

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