TESS Asteroseismology of the Known Red-giant Host Stars HD 212771 and HD 203949
TESS Asteroseismology of the Known Red-giant Host Stars HD 212771 and HD 203949
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DOI：
10.3847/1538-4357/ab44a8
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发表时间：
2019-09
期刊：
影响因子：
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通讯作者：
T. Campante;E. Corsaro;M. Lund;B. Mosser;A. Serenelli;D. Veras;V. Adibekyan;H. M. Antia;W. Ball-W.
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文献类型：
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作者：
T. Campante;E. Corsaro;M. Lund;B. Mosser;A. Serenelli;D. Veras;V. Adibekyan;H. M. Antia;W. Ball-W.
凌日系外行星调查卫星（TESS）正在对经过明亮恒星的行星进行近乎全天的调查。此外，其出色的测光精度使太阳型和红巨星的星震学成为可能，这些恒星表现出对流驱动的类似太阳的振荡。模拟预测，TESS将在近100颗已知的恒星中探测到类似太阳的振荡。在本文中，我们提出了一个已知的红巨星宿主星HD 212771和HD 203949，这两个系统都有一个长周期的行星通过径向速度检测的星震分析。这是TESS首次探测到先前已知的系外行星宿主恒星的振荡，进一步展示了使命对红巨星进行星震学的潜力。我们估计这两颗恒星的基本属性，通过基于网格的建模方法，使用全球asteroseismic参数作为输入。我们深入讨论了HD 203949的演化状态，并注意到它的星震质量（红巨星分支中的M* = 1.23 ± 0.15 M，或星团中的M* = 1.00 ± 0.16 M）与发现论文中引用的质量（M* = 2.1 ± 0.1 M）之间的巨大差异，这意味着行星质量的变化>30%。假设HD 203949在星团中，我们研究了这颗行星过去的轨道演化，并讨论了它如何避免被红巨星分支的尖端吞没。最后，HD 212771在其第三次活动期间被K2观测到，从而可以对TESS和K2的小行星地震性能进行初步比较。我们估计这颗星星观测到的振荡幅度的比值是，与预期的比值0.85一致，这是由于TESS的红带通。
The Transiting Exoplanet Survey Satellite (TESS) is performing a near all-sky survey for planets that transit bright stars. In addition, its excellent photometric precision enables asteroseismology of solar-type and red-giant stars, which exhibit convection-driven, solar-like oscillations. Simulations predict that TESS will detect solar-like oscillations in nearly 100 stars already known to host planets. In this paper, we present an asteroseismic analysis of the known red-giant host stars HD 212771 and HD 203949, both systems having a long-period planet detected through radial velocities. These are the first detections of oscillations in previously known exoplanet-host stars by TESS, further showcasing the mission’s potential to conduct asteroseismology of red-giant stars. We estimate the fundamental properties of both stars through a grid-based modeling approach that uses global asteroseismic parameters as input. We discuss the evolutionary state of HD 203949 in depth and note the large discrepancy between its asteroseismic mass (M* = 1.23 ± 0.15 M⊙ if on the red-giant branch or M* = 1.00 ± 0.16 M⊙ if in the clump) and the mass quoted in the discovery paper (M* = 2.1 ± 0.1 M⊙), implying a change >30% in the planet’s mass. Assuming HD 203949 to be in the clump, we investigate the planet’s past orbital evolution and discuss how it could have avoided engulfment at the tip of the red-giant branch. Finally, HD 212771 was observed by K2 during its Campaign 3, thus allowing for a preliminary comparison of the asteroseismic performances of TESS and K2. We estimate the ratio of the observed oscillation amplitudes for this star to be , consistent with the expected ratio of ∼0.85 due to the redder bandpass of TESS.