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arXiv 1702.03170astro-ph.SRastro-ph.EP
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外行星宿主F-型恒星鲸鱼座94的星震学:原子扩散对恒星参数的影响

Asteroseismology of the exoplanet-host F-type star 94 Ceti : impact of atomic diffusion on the stellar parameters

M. Deal, M. E. Escobar, S. Vauclair, G. Vauclair, A. Hui-Bon-Hoa, O. Richard

摘要:

为了正确地描述行星本身,需要对系外行星宿主恒星的参数进行百分之一的精度。这将通过星震学来实现。在这种情况下,重要的是要测试的影响,在模型中引入原子扩散与辐射加速导出的参数。在本文中,我们以鲸鱼座94 A星为例开始这项研究。我们进行了一个完整的星震分析的系外行星主机F型恒星94鲸鱼座A,从第一径向速度观测与HARPS到最终计算的最佳模型。这颗恒星的温度足以承受原子扩散的重要影响,包括辐射加速。我们测试了这种影响的计算频率和确定的恒星参数。我们还测试了在恒星模型中包含完整大气层的效果。2007年用HARPS进行了径向速度观测。利用经典方法推导并识别了低阶模,并与用Toulouse Geneva演化程序(TGEC)计算的恒星模型结果进行了比较。我们获得了鲸鱼座94 A星的精确参数。我们表明,包括原子扩散与辐射加速可以修改几个百分点的年龄,而添加一个完整的大气不会改变结果超过百分之一。

英文摘要:

A precision of order one percent is needed on the parameters of exoplanet-hosts stars in order to correctly characterize the planets themselves. This will be achieved by asteroseismology. It is important in this context to test the influence on the derived parameters of introducing atomic diffusion with radiative accelerations in the models. In this paper, we begin this study with the case of the star 94 Ceti A. We performed a complete asteroseismic analysis of the exoplanet-host F-type star 94 Ceti A, from the first radial-velocity observations with HARPS up to the final computed best models. This star is hot enough to suffer from important effects of atomic diffusion, including radiative accelerations. We tested the influence of such effects on the computed frequencies and on the determined stellar parameters. We also tested the effect of including a complete atmosphere in the stellar models. The radial velocity observations were done with HARPS in 2007. The low degree modes were derived and identified using classical methods and compared with the results obtained from stellar models computed with the Toulouse Geneva Evolution Code (TGEC). We obtained precise parameters for the star 94 Ceti A. We showed that including atomic diffusion with radiative accelerations can modify the age by a few percents, whereas adding a complete atmosphere does not change the results by more than one percent.

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