论文标题
通过粘性决定模型确定的恒星的角动量损失率
Angular Momentum Loss Rates in Be Stars Determined by the Viscous Decretion Disc Model
论文作者
论文摘要
恒星周围的双眼盘是由中央恒星弹出的材料形成的。由于粘度有助于圆盘内的质量和角动量转移及其生长，因此此过程从恒星中消除了恒星的过量动量。恒星的角动量损失率（AMLR）是文献中争论的主题。通过从BE恒星观察到的圆盘形成和耗散阶段的建模，可以确定它们的平均AMLR，这是这项工作的目标。我们使用粘性决策盘（VDD）模型为恒星提供一系列平均AMLR，并将这些速率与文献预测的值进行比较。我们探讨了使用VDD和日内瓦恒星进化（GSE）模型（以前在文献中报道过的，发现恒星旋转低于其临界速度时发生的最大差异）之间的平均AMLR预测值之间存在差异的原因。我们表明，质量储层建立的时间与平均AMLR成反比。同样，我们确定银河系的平均AMLR的修订值为4.7 x10^36 g cm^2/s^2的星形欧米茄CMA，这与典型B2型星的预期值更一致。最后，研究了由于存在伴侣恒星而引起的圆盘截断的影响，我们发现这对平均AMLR的影响最小。
Circumstellar discs around Be stars are formed by the material ejected by the central star. This process removes excess angular momentum from the star as viscosity facilitates the mass and angular momentum transfer within the disc and its growth. The angular momentum loss rates (AMLR) of Be stars is a subject of debate in the literature. Through the modelling of the disc formation and dissipation phases observed from Be stars, their average AMLR can be determined and this is the goal of this work. We use the viscous decretion disc (VDD) model to provide a range of the average AMLR for Be stars and compare these rates with predicted values from the literature. We explore the reasons for discrepancies between the predicted values of average AMLR using the VDD and Geneva stellar evolution (GSE) models that were previously reported in literature and find that the largest differences occur when Be stars are rotating below their critical speeds. We show that the time over which the mass reservoir builds up is inversely proportional to the average AMLR. Also, we determine a revised value of the average AMLR for the Galactic Be star omega CMa of 4.7x10^36 g cm^2/s^2, which is in better agreement with the values expected for a typical B2 type star. Finally, the effect of disc truncation due to the presence of a companion star is investigated and we find that this has a minimal effect on the average AMLR.
