Tolman-Oppenheimer-Volkoff limit
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The Tolman-Oppenheimer-Volkoff (TOV) limit is an upper bound to the mass of stars composed of neutron-degenerate matter (neutron stars). It is analogous to the Chandrasekhar limit for white dwarf stars.
The limit was computed by Julius Robert Oppenheimer and George Michael Volkoff in 1939, using work of Richard Chace Tolman. Oppenheimer and Volkoff assumed that the neutrons in a neutron star formed a cold, degenerate Fermi gas. This leads to a limiting mass of approximately 0.7 solar masses.[1],[2] Modern estimates range from approximately 1.5 to 3.0 solar masses.[3] The uncertainty in the value reflects the fact that the equations of state for dense hadronic matter are not well-known.
Below the limit, the weight of a neutron star can be supported by short-range repulsive neutron-neutron interactions mediated by the strong force in combination with the quantum degeneracy pressure of neutrons. Above the TOV limit, an object will either collapse to form a black hole, or change composition and be supported in some other way (for example, by quark degeneracy pressure if it becomes a quark star).
Because the properties of hypothetical more exotic forms of degenerate matter are even more poorly known than those of neutron-degenerate matter, most astrophysicists assume, in the absence of evidence to the contrary, that a neutron star above the limit collapses directly into a black hole.
[edit] References
- ^ Static Solutions of Einstein's Field Equations for Spheres of Fluid, Richard C. Tolman, Physical Review 55, #374 (February 15, 1939), pp. 364–373.
- ^ On Massive Neutron Cores, J. R. Oppenheimer and G. M. Volkoff, Physical Review 55, #374 (February 15, 1939), pp. 374–381.
- ^ Bombaci, I. (1996). "The maximum mass of a neutron star". Astronomy and Astrophysics 305: 871-877.
[edit] See also
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