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arXiv 1109.4076astro-ph.SR
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亚矮星B混合核中振荡和转动之间的Angular momentum转换

Angular momentum transfer between oscillations and rotation in subdwarf B hybrid pulsators

Fernando Pérez Hernández, Raquel Oreiro, Haili Hu

摘要:

上下文亚矮星B型超新星具有压力(p)和/或重力(g)模式。它们的频谱范围从非常简单的几个频率到非常丰富的,在某些情况下有超过50个峰值。子09是一颗溷合脉动次矮星B,显示出大量的p模和g模,包括三重态和五重态结构,这些结构被解释为由于恒星旋转而导致的p模频率分裂。在随后的两年中进行的光度观测显示,这些旋转分裂的变化为0.24 - 0.58 μHz/年。目标。我们分析了恒星自转和内部重力波之间的角动量交换作为观测到的旋转分裂变化的机制的可能性。方法.在旋转分裂的本征模从这种机制产生的预期变化计算在非绝热线性近似的恒星结构模型,是代表的目标恒星。g-模式也被观察到的事实使它成为一个特别适合我们的研究候选人,因为在旋转分裂的变化是成比例的振幅平方的g-模式,在这种情况下,可以估计从观察。结果我们发现,这种机制是能够预测的分裂,可以是相同的数量级的变化所观察到的变化的变化。

英文摘要:

Context. Subdwarf B pulsators exhibit pressure (p) and/or gravity (g) modes. Their frequency spectra range from very simple, with few frequencies, to very rich, with more than fifty peaks in some cases. Balloon09 is a hybrid pulsating subdwarf B, showing a large number of p- and g-modes including a triplet and a quintuplet-like structures which are interpreted as p-mode frequency splittings due to stellar rotation. Photometric observations undertaken in two subsequent years revealed a change in these rotational splittings of 0.24 - 0.58 μHz/yr. Aims. We analyse the possibility of angular momentum interchange between stellar rotation and internal gravity waves as a mechanism for the observed rotational splitting variations. Methods. The expected change in the rotational splitting of eigenmodes resulting from this mechanism are computed in the nonadiabatic linear approximation for a stellar structure model that is representative of the target star. The fact that g-modes are also observed in Balloon09 makes it a particularly suitable candidate for our study, because the change in the rotational splittings are proportional to the amplitude squared of the g-modes which, in this case, can be estimated from the observations. Results. We find that this mechanism is able to predict changes in the splittings that can be of the same order of magnitude as the observed variations.

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