http://arxiv.org/abs/1709.01635
In this work we investigate the structure of white dwarfs using the Tolman-Oppenheimer-Volkoff equations and compare our results with those obtained from Newtonian equations of gravitation in order to put in evidence the importance of General Relativity for the structure of such stars.
We consider in this work for the matter inside white dwarfs two equations of state, frequently found in the literature, namely, the Chandrasekhar and Salpeter equations of state.
We find that using Newtonian equilibrium equations, the radii of massive white dwarfs ($M>1.3M_{\odot}$) are overestimated in comparison with General Relativity outcomes. For a mass of $1.41M_{\odot}$ the white dwarf radius predicted by General Relativity is about 50\% smaller than Newtonian one. Hence, in this case, for the surface gravity the difference between the general relativistic and Newtonian outcomes is about 55\%. This discrepancy is mainly due to the fact that hydrostatic equilibrium, in a general relativistic framework, depends on the pressure of the system. We depict the general relativistic mass-radius diagrams as $M/M_{\odot}=R/(a+bR+cR^2+dR^3+kR^4)$, where $a$, $b$, $c$ and $d$ are free parameters and $k=(2.08\times 10^{-6}R_{\odot})^{-1}$, being $R_{\odot}$ the radius of the Sun in $km$. Lastly, we point out that General Relativity plays an important role to dertemine any physical quantity that depends, simultaneously, on the mass and radius of massive white dwarfs.
G. Carvalho, R. Marinho and M. Malheiro
Thu, 7 Sep 17
43/65
Comments: N/A
You must be logged in to post a comment.