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双中子星系统J1846-0513的前身星演化

Progenitor Evolution of the Double Neutron Star System J1846-0513

  • 摘要: J1846-0513是中国自主研发的500 m口径球面射电望远镜发现的毫秒脉冲星双星. 数据分析得到其轨道周期为Porb = 0.613 d, 轨道偏心率为e = 0.208. 根据双星演化理论, 该系统的轨道偏心率极有可能是在伴星发生超新星爆发形成中子星的过程中形成的. 根据质量参数, 该系统被认定为双中子星候选系统. 鉴于该系统的前身星演化对理解恒星和双星演化具有重要意义, 利用恒星演化程序模拟了由初始质量为1.345 M⊙的中子星和初始质量为2.8 M⊙的氦星组成, 初始轨道周期为0.5 d的双星系统的演化. 模拟显示, 氦星质量最终降低到1.554 M⊙, 其中碳氧核质量为1.431 M⊙. 演化结束时, 氦星中心演化出大约0.846 M⊙的硅核和大约0.086 M⊙的铁核及富中子核, 表明该氦星将发生铁核塌缩型超新星爆发, 形成一颗与观测到的质量下限接近的中子星. 对超新星爆发所导致的双星系统轨道骤变的模拟显示, 该模型可以演化为观测到的椭圆轨道双中子星候选体.

     

    Abstract: J1846-0513 is a millisecond pulsar discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) which is stablished by China. Data analysis of observation reveals that the pulsar is harbored in a binary with orbital period of Porb = 0.613 d and ccentricity of e = 0.208. According to the theory of binary evolution, its eccentricity originates from an asymmetric supernova explosion during which the second neutron star burn. Together with the observed parameters of component mass, the binary is assumed to be a double neutron star system candidate. Considering its importance to understand the evolution of stars and binaries, in current work, we simulated the evolution of neutron star - helium (He) star system with initial mass of 1.345 M⊙ and 2.8 M⊙, respectively, and initial orbital period of 0.5 day.At the end of simulation, the total mass of the He star is reduced to 1.556M⊙ with a carbon-oxygen core with mass of 1.431 M⊙. A silicon core of mass 0.846 M⊙ and an iron/neutron-rich core of mass 0.086M⊙ formed in the He star which illustrate it will end with core collapse supernova and born a neutron star with mass of its lower limit. Subsequent simulation of dynamical effects of the supernova explosion indicates that current model may evolve to the observed eccentric double neutron star candidate.

     

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