Premium
Report on the physical characteristics of Vaidya‐Tikekar's exact relativistic model for a superdense star
Author(s) -
Knutsen H.
Publication year - 1988
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.2113090417
Subject(s) - physics , radius , adiabatic process , schwarzschild radius , speed of sound , star (game theory) , center (category theory) , astrophysics , schwarzschild metric , classical mechanics , polytrope , quantum mechanics , gravitation , general relativity , chemistry , computer security , computer science , crystallography , polytropic process
We report here the results of our examination of the physical properties of Vaidya‐Tikekar's model for a relativistic star. Full details will be published elsewhere. The analysis yields a strong indication that the model is stable with respect to infinitesimal radial oscillations. We find that the adiabatic speed of sound is smaller than the speed of light everywhere inside the fluid sphere if the radius of the sphere is larger than 1.46 times its Schwarzschild radius. We also find that the fluid must necessarily be supraluminal somewhere if the speed of sound is decreasing outwards close to the center. We further find that the strong energy condition is fulfilled everywhere if it is fulfilled at the center. Since the ratio of the pressure p and the density ⋅ is decreasing outwards, this indicates that the temperature gradient is negative. We also find that the relativistic adiabatic index is larger than two. Demanding the fluid to be causal, and taking the pressure and the density to be somewhere given by 7.4 ⋅ 10 33 dynes/cm 3 and 5.1 ⋅ 10 14 g/cm 3 , we calculate the maximum mass of the fluid sphere to be 3 solar masses.