Asteroseismology of the Hyades red giant and planet host ϵ Tauri
Asteroseismology of the Hyades red giant and planet host ϵ Tauri
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DOI：
10.1051/0004-6361/201834690
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发表时间：
2019-01
影响因子：
6.5
通讯作者：
T. Arentoft;F. Grundahl;T. White;D. Slumstrup;R. Handberg;M. Lund;K. Brogaard;M. F. Andersen
中科院分区：
文献类型：
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作者：
T. Arentoft;F. Grundahl;T. White;D. Slumstrup;R. Handberg;M. Lund;K. Brogaard;M. F. Andersen
上下文。对类太阳恒星的星震分析使我们能够确定恒星质量等物理参数，与大多数其他方法相比，具有更高的精度。即使在像毕宿四这样研究得很充分的星系团中，红巨星的质量也并不为人所知，之前的质量估计都是基于模型计算(等时线)。根据它们在颜色-星等图中的位置，毕星座的四颗已知的红巨星被认为是团块(燃烧核心氦的)恒星，然而，星震学提供了一个检验这一假设的机会。目标。使用星震技术结合其他方法，我们的目标是得出行星的物理参数和演化阶段的恒星ϵTau，这是四个红色巨星之一位于毕宿四。方法：研究方法。我们分析了地面和空间的时间序列数据，以进行星震分析。通过结合来自地面SONG网络的高信噪比径向速度数据和来自修订的开普勒任务K2的连续空间数据，我们推导和表征了ϵTAU的27个单独的振荡模式，以及全球振荡参数，如大频率间隔Δν和以径向速度测量的振荡幅度与强度之比作为频率的函数。后者之前只对太阳和参宿三两颗恒星进行了测量。结合地震分析、干涉测量和光谱测量，我们得到了ϵ的物理参数，并讨论了它的演化状态。结果。与其他物理参数一起，我们得到了ϵTau的星震质量M=2.458±0.073 M⊙，略低于先前的估计，这导致了修正后的行星伴星的最小质量。注意到SONG和K2数据是不同步的，我们估计强度与径向速度的振幅比为42.2±2.3ppm−1 S，这比从标度关系中预计的要高。
Context. Asteroseismic analysis of solar-like stars allows us to determine physical parameters such as stellar mass, with a higher precision compared to most other methods. Even in a well-studied cluster such as the Hyades, the masses of the red giant stars are not well known, and previous mass estimates are based on model calculations (isochrones). The four known red giants in the Hyades are assumed to be clump (core-helium-burning) stars based on their positions in colour-magnitude diagrams, however asteroseismology offers an opportunity to test this assumption. Aims. Using asteroseismic techniques combined with other methods, we aim to derive physical parameters and the evolutionary stage for the planet hosting star ϵ Tau, which is one of the four red giants located in the Hyades. Methods. We analysed time-series data from both ground and space to perform the asteroseismic analysis. By combining high signal-to-noise radial-velocity data from the ground-based SONG network with continuous space-based data from the revised Kepler mission K2, we derive and characterize 27 individual oscillation modes for ϵ Tau, along with global oscillation parameters such as the large frequency separation Δν and the ratio between the amplitude of the oscillations measured in radial velocity and intensity as a function of frequency. The latter has been measured previously for only two stars, the Sun and Procyon. Combining the seismic analysis with interferometric and spectroscopic measurements, we derive physical parameters for ϵ Tau, and discuss its evolutionary status. Results. Along with other physical parameters, we derive an asteroseismic mass for ϵ Tau of M = 2.458 ± 0.073 M⊙, which is slightly lower than previous estimates, and which leads to a revised minimum mass of the planetary companion. Noting that the SONG and K2 data are non-simultaneous, we estimate the amplitude ratio between intensity and radial velocity to be 42.2 ± 2.3 ppm m−1 s, which is higher than expected from scaling relations.