General relativistic calculations for white dwarfs

• 来源期刊: 天文和天体物理学研究
• 年，卷（期）: 2017,（6）
• 页码范围: 107-116
• 页数: 10页
• 语种: 英文
• DOI: 10.1088/1674-4527/17/6/61

摘要

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 24He (and 126C) white dwarfs.Using the same general relativistic treatment,the critical mass for 5626Fe 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 42He,1.3916 M☉ for 126C and 1.1565 M☉ for 25626Fe white dwarfs.We also compare the critical densities for gravitational instability with the neutronization threshold densities to find that 24He and 126C white dwarfs are stable against neutronization with the critical values of 1.4081 Mo and 1.3916 M☉,respectively.However,the critical masses for 186O,2010Ne,2412Mg,2814Si,3216S 5626Fe white dwarfs are 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.