论文标题
W Vir脉动变量的进化状态
Evolutionary status of W Vir pulsating variables
论文作者
论文摘要
人口II星的恒星演变计算，具有初始组成$ y_0 = 0.25 $，$ z_0 = 10^{ - 3} $，初始恒星质量$ m_0 = 0.82m_ \ odot $是从主序列到白色矮人阶段的主序列进行的。在阻止者质量损失率公式中使用参数的不同值（$ 0.01 \leη_b\ le 0.12 $）计算了12个AGB和POST-AGB进化序列。质量$ m = 0.536m_ \ odot $，$ 0.53万$ \ odot $和$ 0.526万$ $ m = 0.536m__ \ odot $的选定模型的序列模型，因为最终的氦气闪光灯是用作水平动力学的最初条件来描述hertzsprung- russel图，而hertzsprung-russel图中经历了循环。证明径向基本模式脉动的不稳定区域从渐近巨型分支延伸到高达$ t_ \ mathrm {eff} \ 6 \ times 10^3 $ k的有效温度。流体动力学模型的脉冲周期在15天至50天内，并与脉动脉冲的脉冲脉冲相一致。具有周期$π> 50美元的中间光谱类型基本模式脉动器的模型位于Hertzsprung-ussel图的上部，在半牙脉冲变量的区域中。我们得出的结论是，脉动变量是经历最终氦气闪光的低质量柱 - AGB恒星。
Stellar evolution calculations for population II stars with initial composition $Y_0=0.25$, $Z_0=10^{-3}$ and the initial stellar mass $M_0 = 0.82M_\odot$ were carried out from the main sequence to the white dwarf stage. Twelve AGB and post--AGB evolutionary sequences were computed with different values of the parameter in the Blocker mass loss rate formula ($0.01\leη_B\le 0.12$). Selected models of evolutionary sequences with masses $M=0.536M_\odot$, $0.530M_\odot$ and $0.526M_\odot$ that experience the loop in the Hertzsprung--Russel diagram due to the final helium flash were used as initial conditions for solution of the equations of hydrodynamics describing radial stellar oscillations. The region of instability to radial fundamental mode pulsations is shown to extend from the asymptotic giant branch to effective temperatures as high as $T_\mathrm{eff}\approx 6\times 10^3$ K. Pulsation periods of hydrodynamic models are in the range from 15 to 50 day and agree with periods of W~Vir pulsating stars. The models of intermediate spectral type fundamental mode pulsators with periods $Π> 50$ day locate in the upper part of the Hertzsprung--Russel diagram in the region of semiregular pulsating variables. We conclude that W~Vir pulsating variables are the low--mass post--AGB stars that experience the final helium flash.
