Evolution of isolated white dwarfs

Abstract

Abstact. We consider evolution of isolated general relativistic uniformly-rotating white dwarfs which lose angular momentum via magnetic dipole braking. We show for selected constant mass sequences how the main parameters of white dwarfs such as the central density, mean radius and magneticfield change with time by fullling all stability criteria of the general relativistic uniformly-rotating congurations. Namely, we explicitly demonstrate that all isolated white dwarfs by angular momentum loss will be shrinking in order to reach stable equilibrium states.

Time evolution of rotating and magnetized white dwarf stars

“…(1) we obtain two separate equations that describe the evolution of a considered parameter with time taking into account two cases when magnetic field is constant and when magnetic flux is conserved. The behavior of the central density, mean radius and the magnetic field intensity as a function of the characteristic lifetime for both cases have been investigated by Boshkayev et al (2014a). Similar analyses have been performed for the angular velocity as a function of the characteristic lifetime by Boshkayev et al (2017).…”

“…The behavior of the central density, mean radius and the magnetic field intensity as a function of the characteristic lifetime for both cases have been investigated by Boshkayev et al (2014a). Similar analyses have been performed for the angular velocity as a function of the characteristic lifetime by Boshkayev et al (2017).…”

“…To investigate the evolution of isolated white dwarfs with time we made use of Eq. ( 1) and modified it depending on what parameter we are interested in (see (Boshkayev et al 2014a(Boshkayev et al , 2017 for details). Consequently, we adopt two cases: 1) when the magnetic field is constant and 2) when magnetic flux is conserved…”

“…Besides the above timing features, we shall quantify the compression that the WD suffers while evolving via angular momentum loss which is relevant for some models of type Ia supernovae. Specifically, we focus on the compression of isolated zerotemperature super-Chandrasekhar WDs and their isothermal cores by angular momentum loss based on our previous results (Boshkayev et al 2013b(Boshkayev et al , 2014a(Boshkayev et al ,b, 2017. We shall estimate the lifetime (τ ) of zero temperature WDs via magnetic dipole braking taking into due account the effect of the time evolution of all relevant parameters of the WDs.…”

“…In addition, for hot isothermal WD cores we compute the times of the nuclear burning and neutrino emission phenomena. For both cold and hot WDs, we consider two magnetic field evolution: (1) a constant magnetic field during the entire evolution and, (2) a varying magnetic field according to magnetic flux conservation (Boshkayev et al 2014a(Boshkayev et al ,b, 2017.…”