Beta UMi中的振荡-使用SMEI的观测
Oscillations in Beta UMi - Observations with SMEI
摘要：
目的：通过对K4 III恒星Beta UMi的观测，我们试图确定是否存在振荡或任何其他形式的变异。研究方法：分析了从Coriolis卫星上的SMEI仪器获得的长度约为1000天的高质量测光时间序列。进行各种统计检验以确定在光变曲线的功率密度谱中看到的特征的显著性。结果：两个振荡频率为2.44和2.92微赫兹已被确定。我们解释这些振荡连续泛音的声谱，这意味着一个大的频率间隔为0.48微赫兹。使用衍生的星震参数结合已知的天体物理参数，我们估计β UMi的质量为1.3 +/- 0.3太阳质量。功率密度谱中的振荡峰显示宽度，这意味着模式是随机激励和对流阻尼。模式寿命估计为18 +/- 9天。
英文摘要：
Aims: From observations of the K4III star Beta UMi we attempt to determine whether oscillations or any other form of variability is present. Methods: A high-quality photometric time series of approximately 1000 days in length obtained from the SMEI instrument on the Coriolis satellite is analysed. Various statistical tests were performed to determine the significance of features seen in the power density spectrum of the light curve. Results: Two oscillations with frequencies 2.44 and 2.92 microhertz have been identified. We interpret these oscillations as consecutive overtones of an acoustic spectrum, implying a large frequency spacing of 0.48 microhertz. Using derived asteroseismic parameters in combination with known astrophysical parameters, we estimate the mass of Beta UMi to be 1.3 +/- 0.3 solar masses. Peaks of the oscillations in the power density spectrum show width, implying that modes are stochastically excited and damped by convection. The mode lifetime is estimated at 18 +/- 9 days.
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