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arXiv 1402.4833astro-ph.EP
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非同步旋转热彗星的大气环流和可观测性质

The Atmospheric Circulation and Observable Properties of Non-Synchronously Rotating Hot Jupiters

E. Rauscher, E. M. R. Kempton

摘要:

我们研究的可行性,观测约束的旋转速率的热行星,通常假设已被潮汐锁定到同步旋转的行星。我们使用三维大气环流模型来求解两个热彗星(HD 189733b和HD 209458b)的大气结构,假设旋转周期是它们轨道周期的0.5、1或2倍(分别为2.2和3.3天),包括可变恒星加热的影响。我们比较了两个可观测的特性:1)行星发射的通量的空间变化,可在轨道相位曲线中测量,2)大气传输光谱中的净多普勒频移,这非常接近于在高分辨率过境光谱中测量。虽然我们发现HD 189733b的同步和非同步模型的可观测特性之间几乎没有差异,但当我们比较HD 209458b的模型时,我们看到了显着的差异。特别是,HD 209458 b的缓慢旋转模型具有向西流动的大气环流模式和在二次日食后达到峰值的轨道相位曲线(与我们所有其他模型相反),而快速旋转模型的净多普勒频移比其他模型更强烈。我们的研究结果表明,这两种技术的结合使用可能是一个富有成效的方式来限制一些行星的旋转速率,并激励未来的工作在这个话题上。

英文摘要:

We study the feasibility of observationally constraining the rotation rate of hot Jupiters, planets that are typically assumed to have been tidally locked into synchronous rotation. We use a three-dimensional General Circulation Model to solve for the atmospheric structure of two hot Jupiters (HD 189733b and HD 209458b), assuming rotation periods that are 0.5, 1, or 2 times their orbital periods (2.2 and 3.3 days, respectively), including the effect of variable stellar heating. We compare two observable properties: 1) the spatial variation of flux emitted by the planet, measurable in orbital phase curves, and 2) the net Doppler shift in transmission spectra of the atmosphere, which is tantalizingly close to being measurable in high-resolution transit spectra. Although we find little difference between the observable properties of the synchronous and non-synchronous models of HD 189733b, we see significant differences when we compare the models of HD 209458b. In particular, the slowly rotating model of HD 209458b has an atmospheric circulation pattern characterized by westward flow and an orbital phase curve that peaks after secondary eclipse (in contrast to all of our other models), while the quickly rotating model has a net Doppler shift that is more strongly blue-shifted than the other models. Our results demonstrate that the combined use of these two techniques may be a fruitful way to constrain the rotation rate of some planets, and motivate future work on this topic.

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。

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