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arXiv 1010.4585astro-ph.EPastro-ph.SR
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关于热木星大气中热逆温的推断

On the Inference of Thermal Inversions in Hot Jupiter Atmospheres

N. Madhusudhan, S. Seager

摘要:

最近的几项研究已经推断出在一些过境的热木星大气中存在热反转。由于现有数据有限,逆温的推断主要取决于大气的化学成分。在这项研究中,我们探讨了热反转和分子丰度之间的退化在四个高度辐照热木星大气,白天的观测,其中以前报道的是一致的热反转的基础上斯皮策测光。这四个系统是:HD 209458 b、HAT-P-7 b、TrES-4和TrES-2。对于每个系统,我们使用马尔可夫链蒙特卡罗例程探索具有约10^6个模型的模型参数空间。我们的研究结果主要表明,彻底探索的模型参数空间是必要的,以确定热木星大气中的热反转。我们发现,现有的观察TrES-4和TrES-2都可以非常精确地拟合模型与热反演和没有热反演,并具有广泛的化学成分。另一方面,HD 209458 b和HAT-P-7 b的观测结果与热逆的拟合比没有更好,正如以前报道的那样。根据目前的数据,我们没有看到辐射水平和热反转之间的相关性。在JWST可用之前,来自地面和HST的近红外观测,以及现有的斯皮策观测,可以潜在地解决某些系统中的热逆。

英文摘要:

Several studies in the recent past have inferred the existence of thermal inversions in some transiting hot Jupiter atmospheres. Given the limited data available, the inference of a thermal inversion depends critically on the chemical composition assumed for the atmosphere. In this study, we explore the degeneracies between thermal inversions and molecular abundances in four highly irradiated hot Jupiter atmospheres, day-side observations of which were previously reported to be consistent with thermal inversions based on Spitzer photometry. The four systems are: HD 209458b, HAT-P-7b, TrES-4, and TrES-2. For each system, we explore the model parameter space with ~ 10^6 models using a Markov chain Monte Carlo routine. Our results primarily suggest that a thorough exploration of the model parameter space is necessary to identify thermal inversions in hot Jupiter atmospheres. We find that existing observations of TrES-4 and TrES-2 can both be fit very precisely with models with and without thermal inversions, and with a wide range in chemical composition. On the other hand, observations of HD 209458b and HAT-P-7b are better fit with thermal inversions than without, as has been reported before. We do not see a correlation between irradiation levels and thermal inversions, given current data. Before JWST becomes available, near-IR observations from ground and with HST, along with existing Spitzer observations, can potentially resolve thermal inversions in some systems.

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