Wolf-Rayet双星中潮汐增强质量损失对偏心率激发的限制
Limits on eccentricity excitation by tidally enhanced mass loss in Wolf-Rayet binaries
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中文总结 AI 辅助
该研究通过建模14个Wolf-Rayet双星系统，检验潮汐增强质量损失能否激发高偏心率，发现其激发幅度远低于观测值，表明高偏心率主要源于原生而非WR阶段产生。
中文摘要 AI 辅助
Wolf-Rayet（WR）双星经常表现出高轨道偏心率，且其偏心率分布与高质量银河系场双星在高度显著性水平上不一致。这引发了一个问题：这些偏心率是原生的还是在WR阶段产生的。我们测试了潮汐增强的质量损失率是否能在14个WR系统的样本中激发WR双星的偏心率。我们将每个系统建模为变质量二体问题，并在三种方案下对WR寿命期间的轨道演化进行积分：i）绝热各向同性质量损失，ii）平衡潮汐圆化，以及iii）潮汐增强的、近心点聚焦的质量损失，其中伴星朝向面的有效表面重力降低提高了局部爱丁顿参数。绝热质量损失不能改变偏心率，仅影响轨道间距，其增加可达约20倍。潮汐圆化仅在最短轨道中有效，这些轨道仅在高质量损失率下与观测系统兼容，而在此机制下任何原生偏心率都会被抹除。潮汐增强的质量损失通道仅将偏心率激发至≤10^-4，比观测值低三到四个数量级，因此不可能是相关机制。我们得出结论，WR双星的高偏心率主要是原生的，而非在WR阶段由质量损失产生。
英文摘要
Wolf--Rayet (WR) binaries frequently display high orbital eccentricities, and their eccentricity distributions are inconsistent with that of high-mass Galactic field binaries at high significance. This raises the question of whether these eccentricities are primordial or generated during the WR phase. We test whether a tidal enhancement of the mass-loss rate can pump the eccentricity of a WR binary on a sample of 14 WR systems. We model each system as a variable-mass two-body problem and integrate the orbital evolution over the WR lifetime under three prescriptions: i) adiabatic isotropic mass loss, ii) equilibrium-tide circularization, and iii) a tidally enhanced, pericenter-focused mass loss in which the companion-facing reduction of the effective surface gravity raises the local Eddington parameter. Adiabatic mass loss can not change eccentricity and affects only the orbital separation, which increases by up to a factor of ~20. Tidal circularization is effective only in the tightest orbits, which are compatible with the observed systems only for high mass-loss rates, a regime in which any primordial eccentricity is erased. The tidally enhanced mass loss channel pumps the eccentricity by only $\leq10^{-4}$, three to four orders of magnitude below the observed values, and therefore cannot be the responsible mechanism. We conclude that the high eccentricities of WR binaries are predominantly primordial rather than generated by mass loss during the WR phase.
发表机构
- HUN-REN CSFK Konkoly Observatory（匈牙利科学院CSFK孔科利天文台）
- ELTE Eötvös Loránd University, Institute of Physics and Astronomy（厄特沃什·罗兰大学物理与天文学研究所）
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