贫金属亚巨星nu Indi：II中的类太阳振荡。声谱和模式寿命
Solar-like oscillations in the metal-poor subgiant nu Indi: II. Acoustic spectrum and mode lifetime
摘要：
恒星中的对流激发共振声波，共振声波取决于恒星内部的声速，而声速又取决于恒星内部的性质。因此，星震学是探测恒星内部结构的无与伦比的方法。我们对贫金属亚巨星nu Indi进行了地震研究，目的是限制其内部结构。我们的研究是基于时间序列的1201径向速度测量分布在14个晚上从两个站点，在澳大利亚的赛丁泉天文台和ESO在智利的拉西拉天文台。高精度速度时间序列的功率谱在200和500 uHz之间清楚地呈现出几个可识别的峰，显示出在330 uHz处具有25.14 ± 0.09 uHz和2.96 ± 0.22 uHz的大间距和小间距的规律性。已经确定了13个单独的模式，振幅范围为53至173 cm/s。模式衰减时间估计约为16天（1-sigma范围在9到50天之间），比其他恒星如太阳，α Cen系统或巨型xi Hya要长得多。
英文摘要：
Convection in stars excites resonant acoustic waves which depend on the sound speed inside the star, which in turn depends on properties of the stellar interior. Therefore, asteroseismology is an unrivaled method to probe the internal structure of a star. We made a seismic study of the metal-poor subgiant star nu Indi with the goal of constraining its interior structure. Our study is based on a time series of 1201 radial velocity measurements spread over 14 nights obtained from two sites, Siding Spring Observatory in Australia and ESO La Silla Observatory in Chile. The power spectrum of the high precision velocity time series clearly presents several identifiable peaks between 200 and 500 uHz showing regularity with a large and small spacing of 25.14 +- 0.09 uHz and 2.96 +- 0.22 uHz at 330 uHz. Thirteen individual modes have been identified with amplitudes in the range 53 to 173 cm/s. The mode damping time is estimated to be about 16 days (1-sigma range between 9 and 50 days), substantially longer than in other stars like the Sun, the alpha Cen system or the giant xi Hya.
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