The interior rotation of a sample of gamma Doradus stars from ensemble modelling of their gravity mode period spacings
The interior rotation of a sample of gamma Doradus stars from ensemble modelling of their gravity mode period spacings
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DOI：
10.1051/0004-6361/201628616
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发表时间：
2016-07
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影响因子：
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通讯作者：
T. V. Reeth;Andrew Tkachenko;C. Aerts;C. Aerts
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文献类型：
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作者：
T. V. Reeth;Andrew Tkachenko;C. Aerts;C. Aerts
上下文剑鱼座γ星（以下简称为γ Dor星）是已知的表现出重力和/或重力惯性模式，探测对流核心边界附近的恒星内部区域。脉动周期的非等距间隔是恒星演化和当前内部结构的观测特征，并受到旋转的严重影响。目标。我们的目标是限制近核心的旋转速率的伽马多尔星的样本，我们已经检测到的周期间隔模式。方法.我们将渐近周期间距与传统的恒星脉动近似相结合，使用卡方优化来拟合观测到的周期间距模式。该方法被应用到观察到的周期间隔模式的一个样本的恒星，并用于合奏建模。结果对于大多数具有观测到的周期间隔模式的恒星，我们成功地确定了旋转速率和渐近周期间隔值，尽管后者的不确定性裕度通常很大。这也直接导致了与探测到的脉动频率相对应的模式的识别，对于大多数恒星来说，这些模式是双偶极重力模式和重力惯性模式。大多数观察到的逆行模式被发现是Rossby模式。我们进一步讨论了由于忽略了离心力和科里奥利力的不完全处理的方法的局限性。结论尽管目前的局限性，拟议的方法是成功的，从观察到的周期间隔模式，以获得旋转率，并确定模式。它形成了第一步，详细的地震建模的基础上观察到的周期间隔模式的中度到快速旋转的伽玛多尔星。
CONTEXT. Gamma Doradus stars (hereafter gamma Dor stars) are known to exhibit gravity- and/or gravito-intertial modes that probe the inner stellar region near the convective core boundary. The non-equidistant spacing of the pulsation periods is an observational signature of the stars' evolution and current internal structure and is heavily influenced by rotation. AIMS. We aim to constrain the near-core rotation rates for a sample of gamma Dor stars, for which we have detected period spacing patterns. METHODS. We combined the asymptotic period spacing with the traditional approximation of stellar pulsation to fit the observed period spacing patterns using chi-squared optimisation. The method was applied to the observed period spacing patterns of a sample of stars and used for ensemble modelling. RESULTS. For the majority of stars with an observed period spacing pattern we successfully determined the rotation rates and the asymptotic period spacing values, though the uncertainty margins on the latter were typically large. This also resulted directly in the identification of the modes corresponding with the detected pulsation frequencies, which for most stars were prograde dipole gravity and gravito-inertial modes. The majority of the observed retrograde modes were found to be Rossby modes. We further discuss the limitations of the method due to the neglect of the centrifugal force and the incomplete treatment of the Coriolis force. CONCLUSION. Despite its current limitations, the proposed methodology was successful to derive the rotation rates and to identify the modes from the observed period spacing patterns. It forms the first step towards detailed seismic modelling based on observed period spacing patterns of moderately to rapidly rotating gamma Dor stars.