Effect of centrifugal force on transmission spectroscopy of exoplanet atmospheres
Effect of centrifugal force on transmission spectroscopy of exoplanet atmospheres
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离心力对系外行星大气透射光谱的影响
DOI：
10.1093/mnrasl/slad058
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Banerjee A
中科院分区：
文献类型：
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作者：
Banerjee A
透射光谱是了解系外行星大气最成功的方法之一。使用透射光谱进行反演的过程包括创建大量正演模型并将其与观测结果进行比较，以解决限制系外行星大气特性的逆问题。我们探讨了凌日系外行星正演模型常用的一个简化假设的影响：即行星可以被视为一个孤立的、不旋转的球体。行星自转产生的离心加速度与行星大气层的引力相反，并增加了其尺度高度。用于检索的传统正向模型通常不包括这种效应。我们发现，当消除这一假设时，大气反演对于低重力的近距离行星会产生显着不同的结果，例如对于类似于 WASP-19b 的模拟行星，气体丰度的真实值与检索值之间的差异大于 1σ。我们建议在未来分析系外行星的高精度透射光谱时，考虑到由于这种效应而对大气尺度高度的修正，最近的JWSTCycle 1目标是WASP-19b和WASP-121b。
Transmission spectroscopy is one of the most successful methods of learning about exoplanet atmospheres. The process of retrievals using transmission spectroscopy consists of creating numerous forward models and comparing them to observations to solve the inverse problem of constraining the atmospheric properties of exoplanets. We explore the impact of one simplifying assumption commonly employed by forward models of transiting exoplanets: namely that the planet can be treated as an isolated, non-rotating spherical body. The centrifugal acceleration due to a planet’s rotation opposes the gravitational pull on a planet’s atmosphere and increases its scale height. Conventional forward models used for retrievals generally do not include this effect. We find that atmospheric retrievals produce significantly different results for close-in planets with low gravity when this assumption is removed, e.g. differences between true and retrieved values of gas abundances greater than 1σ for a simulated planet analogous to WASP-19b. We recommend that the correction to the atmospheric scale height due to this effect be taken into account for the analysis of high-precision transmission spectra of exoplanets in the future, most immediatelyJWSTCycle 1 targets WASP-19b and WASP-121b.