The mass-radius relations for white dwarfs are investigated by solving the Newtonian as well as Tolman-Oppenheimer-Volkoff （TOV） equations for hydrostatic equilibrium assuming the electron gas to be non-interacting....The mass-radius relations for white dwarfs are investigated by solving the Newtonian as well as Tolman-Oppenheimer-Volkoff （TOV） equations for hydrostatic equilibrium assuming the electron gas to be non-interacting. We find that the Newtonian limiting mass of 1.4562 M is modified to 1.4166 M in the general relativistic case for 4He （and 12 6C） white dwarfs. Using the same general relativistic treatment, the critical mass for 56 26Fe white dwarfs is obtained as 1.2230 M. In addition, departure from the ideal degenerate equation of state （EoS） is accounted for by considering Salpeter＇s EoS along with the TOV equation, yielding slightly lower values for the critical masses, namely 1.4081 M for 4He, 1.3916M for 12C and 1.1565M for 56 26Fe white dwarfs. We also compare the critical densities for gravitational instability with the neutronization threshold densities to find that 4 2He and 12 6C white dwarfs are stable against neutronization with the critical values of 1.4081 M and 1.3916 M, respectively. However, the critical masses for 16 8O, 20 10Ne, 24 12Mg, 28 14Si,32 16S and 56 26Fewhite dwarfs are 26Fe white lower due to neutronization. Corresponding to their central densities for neutronization thresholds, we obtain their maximum stable masses due to neutronization by solving the TOV equation coupled with the Salpeter EoS.展开更多
文摘The mass-radius relations for white dwarfs are investigated by solving the Newtonian as well as Tolman-Oppenheimer-Volkoff （TOV） equations for hydrostatic equilibrium assuming the electron gas to be non-interacting. We find that the Newtonian limiting mass of 1.4562 M is modified to 1.4166 M in the general relativistic case for 4He （and 12 6C） white dwarfs. Using the same general relativistic treatment, the critical mass for 56 26Fe white dwarfs is obtained as 1.2230 M. In addition, departure from the ideal degenerate equation of state （EoS） is accounted for by considering Salpeter＇s EoS along with the TOV equation, yielding slightly lower values for the critical masses, namely 1.4081 M for 4He, 1.3916M for 12C and 1.1565M for 56 26Fe white dwarfs. We also compare the critical densities for gravitational instability with the neutronization threshold densities to find that 4 2He and 12 6C white dwarfs are stable against neutronization with the critical values of 1.4081 M and 1.3916 M, respectively. However, the critical masses for 16 8O, 20 10Ne, 24 12Mg, 28 14Si,32 16S and 56 26Fewhite dwarfs are 26Fe white lower due to neutronization. Corresponding to their central densities for neutronization thresholds, we obtain their maximum stable masses due to neutronization by solving the TOV equation coupled with the Salpeter EoS.
