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Constraints on the central density and chemical composition of the white dwarf RX J0648.0-4418 with a record period of rotation in a model with the equation of state of an ideal degenerate electron gas

  • Physics of Elementary Particles and Atomic Nuclei. Theory
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Abstract

A system of equations and inequalities that allows one to determine the constraints on central density ρ c and the chemical composition, which is governed by parameter μ e , of the white dwarf RX J0648.0- 4418 with a record short period of rotation T = 13.18s and mass m = (1.28 ± 0.05)m⊙, has been derived. The analysis of numerical solutions of this system reveal a complex dependence of μ e on ρ c . The intervals of variation of μ e and ρ c are as follows: 1.09 ≤ μ e ≤ 1.21 and 9.04 ≤ μ e /ρ0 ≤ 103 (ρ0 = 0.98 × 106 g/cm3). This range of μ e values suggests that the white dwarf RX J0648.0-4418 is not made of pure hydrogen and should contain 9–21% of heavy elements. Calculations have been performed with the equation of state of an ideal degenerate electron gas. Approximate analytic expressions (with an accuracy of 10-3) for the minimum period T min and mass m of the white dwarf are obtained. It is demonstrated that the white-dwarf mass is almost doubled (compared to the case of no rotation at a fixed central density) as period T approaches T min.

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Authors and Affiliations

  1. Tver State University, Tver, 170000, Russia

    S. A. Mikheev & V. P. Tsvetkov

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  1. S. A. Mikheev
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  2. V. P. Tsvetkov
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Correspondence to S. A. Mikheev.

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Original Russian Text © S.A. Mikheev, V.P. Tsvetkov, 2016, published in Pis’ma v Zhurnal Fizika Elementarnykh Chastits i Atomnogo Yadra, 2016.

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Mikheev, S.A., Tsvetkov, V.P. Constraints on the central density and chemical composition of the white dwarf RX J0648.0-4418 with a record period of rotation in a model with the equation of state of an ideal degenerate electron gas. Phys. Part. Nuclei Lett. 13, 442–450 (2016). https://doi.org/10.1134/S1547477116040099

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  • DOI: https://doi.org/10.1134/S1547477116040099

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