arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1109.0705astro-ph.SR
收藏

$β\,$ Cep星HD\,180642(V1449 \,Aql)的地震模拟

Seismic modelling of the $β\,$Cep star HD\,180642 (V1449\,Aql)

C. Aerts, M. Briquet, P. Degroote, A. Thoul, T. Van Hoolst

摘要:

我们提出了$β\,$ Cep星HD\,180642的观测特性推导出的CoRoT和地基测光以及从时间分辨光谱学的基础上建模。我们调查目前最先进的模型是否能够解释这颗恒星的完整地震行为,这扩展了这种类型的反射器的观测限制。我们建立了一个专门的恒星模型数据库,通过改变氢含量、金属丰度、质量、年龄和核心过冲参数,调整恒星模型的振荡模式,以适应HD 1,180642的主径向模式频率。我们比较了这些模型的地震特性与观察到的。我们发现的模型,能够解释许多观察到的恒星的振荡特性,为11.4- 11.8\,M $_\odot$的质量范围很窄,没有或非常温和的过冲(高达0.05局部压力标度高度),除了$\ell=3$,p $_1$模式的激发问题。我们推导出一个旋转周期约为13\,d,这是完全符合最近的磁场测量。地震模型并不支持早期恒星中类似太阳振荡的说法。相反,我们归因于在高频率的功率过剩的非线性共振模式之间的高振幅径向基本模式和几个低阶压力模式的耦合。我们在$2.5σ$水平上报告了地震重力和光谱重力之间的差异。

英文摘要:

We present modelling of the $β\,$Cep star HD\,180642 based on its observational properties deduced from CoRoT and ground-based photometry as well as from time-resolved spectroscopy. We investigate whether present-day state-of-the-art models are able to explain the full seismic behaviour of this star, which has extended observational constraints for this type of pulsator. We constructed a dedicated database of stellar models and their oscillation modes tuned to fit the dominant radial mode frequency of HD\,180642, by means of varying the hydrogen content, metallicity, mass, age, and core overshooting parameter. We compared the seismic properties of these models with those observed. We find models that are able to explain the numerous observed oscillation properties of the star, for a narrow range in mass of 11.4--11.8\,M$_\odot$ and no or very mild overshooting (with up to 0.05 local pressure scale heights), except for an excitation problem of the $\ell=3$, p$_1$ mode. We deduce a rotation period of about 13\,d, which is fully compatible with recent magnetic field measurements. The seismic models do not support the earlier claim of solar-like oscillations in the star. We instead ascribe the power excess at high frequency to non-linear resonant mode coupling between the high-amplitude radial fundamental mode and several of the low-order pressure modes. We report a discrepancy between the seismic and spectroscopic gravity at the $2.5σ$ level.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑