当前位置: X-MOL 学术Astron. Lett. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Evolutionary Status of W Vir Pulsating Variables
Astronomy Letters ( IF 0.9 ) Pub Date : 2021-03-19 , DOI: 10.1134/s106377372011002x
Yu. A. Fadeyev

Abstract

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 Blöcker mass loss rate formula (\(0.01\leq\eta_{\textrm{B}}\leq 0.12\)). 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 \(T_{\textrm{eff}}\approx 6\times 10^{3}\) K. Pulsation periods of hydrodynamic models are in the range from 15 to 40 day and agree with periods of W Vir pulsating stars. The models of intermediate spectral type fundamental mode pulsators with periods \(\Pi>40\) 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.



中文翻译:

W Vir脉动变量的进化状态

摘要

具有初始成分\(Y_ {0} = 0.25 \)\(Z_ {0} = 10 ^ {-3} \)和初始恒星质量\(M_ {0} = 0.82M_ {\ odot} \)从主序到白矮星阶段。在Blöcker质量损失率公式(\(0.01 \ leq \ eta _ {\ textrm {B}} \ leq 0.12 \)中,使用不同参数值计算了十二个AGB和后AGB进化序列。质量为\(M = 0.536M _ {\ odot} \)\(0.530M _ {\ odot} \)\(0.526M _ {\ odot} \由于最终的氦气闪蒸,经历赫兹普鲁–罗素图中循环的过程被用作求解描述径向恒星振荡的流体动力学方程的初始条件。径向基本模式脉动的不稳定性区域显示为从渐近巨型分支扩展到有效温度,最高达到\(T _ {\ textrm {eff}} \约6 \乘以10 ^ {3} \ K。的水动力模型范围为15到40天,与W Vir脉动星的周期一致。周期为\(\ Pi> 40 \)的中间谱型基本模式波轮的模型一天位于半规则脉动变量区域的Hertzsprung–Russel图的上部。我们得出的结论是,V Vir脉动变量是经历了最终氦气闪蒸的低质量AGB后恒星。

更新日期:2021-03-19
down
wechat
bug