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arXiv 2103.07185astro-ph.EP
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来自热木星大气垂直混合的不平衡化学的证据。用温暖的斯皮策/IRAC对近距离气体巨系外行星的综合调查

Evidence for disequilibrium chemistry from vertical mixing in hot Jupiter atmospheres. A comprehensive survey of transiting close-in gas giant exoplanets with warm-Spitzer/IRAC

C. Baxter, J-M. Désert, S-M. Tsai, K. O. Todorov, J. L. Bean, D. Deming, V. Parmentier, J. J. Fortney, M. Line, D. Thorngren, R. T. Pierrehumbert, A. Burrows, A. P. Showman

摘要:

[摘要]目的。本文利用Spitzer/IRAC在3.6和4.5 μ m波段的红外透射测光技术对49颗气态巨系外行星进行了大规模的大气研究。方法.我们使用自定义管道统一分析了33个过境行星的70个光度光变曲线,该管道实现了像素级去相关。我们利用这一调查来了解红外测光如何跟踪大气化学性质的变化作为行星温度的函数。我们比较我们的测量网格的一维辐射对流平衡向前大气模型,其中包括不平衡化学。我们探索了垂直混合的各种强度(Kzz = 0 - 10^12 cm 2/s)以及两种化学成分(1x和30 x太阳)。结果我们发现,平均而言,斯皮策探测器探测3.6和4.5微米之间的0.5大气尺度高度的差异,这是在7.5西格玛的显着性水平。我们发现,与预期相比,最冷的行星显示出甲烷的缺乏,这也是以前对单个物体的研究所报道的。我们发现,最冷行星的样本排除了1x太阳成分,置信度>3sigma,同时支持低垂直混合(Kzz = 10^8 cm 2/s)。另一方面,我们发现热行星最好用1x太阳金属丰度和高垂直混合(Kzz = 10^12 cm 2/s)的模型来解释。我们解释这是由于CH 4向大气上层的漂移。改变内部温度会改变对深层平衡化学的预期,因此对不平衡化学的预期会更高。我们还发现了一个显着的分散在传输签名的中温带和超热的行星,可能是由于增加了大气的多样性,而不需要调用更高的金属丰度。此外,我们比较斯皮策传输与排放相同的行星,并没有发现相关性的证据。

英文摘要:

[Abridged] Aims. We present a large atmospheric study of 49 gas giant exoplanets using infrared transmission photometry with Spitzer/IRAC at 3.6 and 4.5um. Methods. We uniformly analyze 70 photometric light curves of 33 transiting planets using our custom pipeline, which implements pixel level decorrelation. We use this survey to understand how infrared photometry traces changes in atmospheric chemical properties as a function of planetary temperature. We compare our measurements to a grid of 1D radiative-convective equilibrium forward atmospheric models which include disequilibrium chemistry. We explore various strengths of vertical mixing (Kzz = 0 - 10^12 cm2/s) as well as two chemical compositions (1x and 30x solar). Results. We find that, on average, Spitzer probes a difference of 0.5 atmospheric scale heights between 3.6 and 4.5um, which is measured at 7.5sigma level of significance. We find that the coolest planets show a lack of methane compared to expectations, which has also been reported by previous studies of individual objects. We show that the sample of coolest planets rule out 1x solar composition with >3sigma confidence while supporting low vertical mixing (Kzz = 10^8 cm2/s). On the other hand, we find that the hot planets are best explained by models with 1x solar metallicity and high vertical mixing (Kzz = 10^12 cm2/s). We interpret this as the lofting of CH4 to the upper atmospheric layers. Changing the interior temperature changes the expectation for equilibrium chemistry in deep layers, hence the expectation of disequilibrium chemistry higher up. We also find a significant scatter in the transmission signatures of the mid-temperate and ultra-hot planets, likely due to increased atmospheric diversity, without the need to invoke higher metallicities. Additionally, we compare Spitzer transmission with emission for the same planets and find no evidence for correlation.

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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