Maximum mass of a barotropic spherical star

Atsuhito Fujisawa, Hiromi Saida, Chul Moon Yoo, Yasusada Nambu

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11 Citations (Scopus)


The ratio of total mass m∗ to the surface radius r of a spherical perfect fluid ball has an upper bound, Gm (c2r) ≤B. Buchdahl (1959 Phys. Rev. 116 1027) obtained the value BBuch = 4 9 under the assumptions that the object has a nonincreasing mass density in the outward direction and a barotropic equation of state. Barraco and Hamity (2002 Phys. Rev. D 65 124028) decreased Buchdahls bound to a lower value, BBaHa = 3/8 (<4/9), by adding the dominant energy condition to Buchdahls assumptions. In this paper, we further decrease Barraco-Hamitys bound to Bnew ≃ 0.3636403 (<3/8) by adding the subluminal (slower than light) condition of sound speed. In our analysis we numerically solve the Tolman-Oppenheimer-Volkoff equations, and the mass-to-radius ratio is maximized by variation of mass, radius and pressure inside the fluid ball as functions of mass density.

Original languageEnglish
Article number215028
JournalClassical and Quantum Gravity
Issue number21
Publication statusPublished - Oct 15 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)


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