CoRoT主要目标HD 52265：模型和抗震试验
The CoRoT primary target HD 52265: models and seismic tests
摘要：
HD 52265是唯一已知的系外行星宿主星，被选为CoRoT卫星地震学方案的主要目标。因此，将在五个月内对它进行连续观测，这在行星系统研究的框架内特别有意义。这颗恒星在亮星表中被误认为是巨星，但它更有可能位于主序星或次巨星分支的开始。我们对这颗恒星进行了广泛的分析，展示了星震学如何精确地确定其外部参数和内部结构。首先回顾了HD 52265的光谱观测对金属丰度、重力和有效温度的观测约束。我们还利用依巴谷视差推导了它的光度。我们计算了各种金属丰度模型的演化轨迹，这些模型跨越重力有效温度平面中的相关观测误差框。我们选择了八个不同的恒星模型，满足观测约束条件，计算其p-模式的频率和分析具体的地震测试。HD 52265的可能模型，满足来自光谱观测的约束条件，是不同的外部和内部参数。它们要么位于主序星上，要么位于次巨星分支的起始处。由于模型的不同，导致了它们的振荡频率特性的差异。我们给出了这些频率的一个有趣的具体行为的证据，在富氦核心的情况下：“小分离”可能会成为负的，并给核心的大小的限制。我们希望CoRoT卫星对这颗恒星的观测将允许在这些可能的模型之间进行选择。
英文摘要：
HD 52265 is the only known exoplanet-host star selected as a main target for the seismology programme of the CoRoT satellite. As such, it will be observed continuously during five months, which is of particular interest in the framework of planetary systems studies. This star was misclassified as a giant in the Bright Star Catalog, while it is more probably on the main-sequence or at the beginning of the subgiant branch. We performed an extensive analysis of this star, showing how asteroseismology may lead to a precise determination of its external parameters and internal structure. We first reviewed the observational constraints on the metallicity, the gravity and the effective temperature derived from the spectroscopic observations of HD 52265. We also derived its luminosity using the Hipparcos parallax. We computed the evolutionary tracks for models of various metallicities which cross the relevant observational error boxes in the gravity-effective temperature plane. We selected eight different stellar models which satisfy the observational constraints, computed their p-modes frequencies and analysed specific seismic tests. The possible models for HD 52265, which satisfy the constraints derived from the spectroscopic observations, are different in both their external and internal parameters. They lie either on the main sequence or at the beginning of the subgiant branch. The differences in the models lead to quite different properties of their oscillation frequencies. We give evidences of an interesting specific behaviour of these frequencies in case of helium-rich cores: the ``small separations'' may become negative and give constraints on the size of the core. We expect that the observations of this star by the CoRoT satellite wi ll allow choosing between these possible models.
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