Impacts from icy and rocky bodies have helped shape the composition of Solar System objects; for example, the Earth–Moon system, or the recent impact of comet Shoemaker–Levy 9 with Jupiter. It is likely that such impacts also shape the composition of exoplanetary systems. Here, we investigate how cometary impacts might affect the atmospheric composition/chemistry of hot Jupiters, which are prime targets for characterization. We introduce a parameterized cometary impact model that includes thermal ablation and pressure driven breakup, which we couple with the 1D “radiative-convective” atmospheric model ATMO, including disequilibrium chemistry. We use this model to investigate a wide range of impactor masses and compositions, including those based on observations of Solar System comets, and interstellar ices (with JWST). We find that even a small impactor (R = 2.5 km) can lead to significant short-term changes in the atmospheric chemistry, including a factor >10 enhancement in H₂O, CO, and CO₂ abundances, as well as atmospheric opacity more generally, and the near-complete removal of observable hydrocarbons, such as CH₄, from the upper atmosphere. These effects scale with the change in atmospheric C/O ratio and metallicity. Potentially observable changes are possible for a body that has undergone significant/continuous bombardment, such that the global atmospheric chemistry has been impacted. Our works reveals that cometary impacts can significantly alter or pollute the atmospheric composition/chemistry of hot Jupiters. These changes have the potential to mute/break the proposed link between atmospheric C/O ratio and planet formation location relative to key snowlines in the natal protoplanetary disk.

中文翻译：

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彗星“影响”对热木星大气层的化学、气候和光谱的影响

冰冷和岩石天体的影响帮助塑造了太阳系天体的组成；例如，地月系统，或者最近舒梅克-利维 9 号彗星与木星的撞击。这些影响很可能也塑造了系外行星系统的组成。在这里，我们研究彗星撞击如何影响热木星的大气成分/化学成分，这是表征的主要目标。我们引入了参数化的彗星撞击模型，其中包括热烧蚀和压力驱动的破碎，我们将其与一维“辐射对流”大气模型 ATMO（包括不平衡化学）相结合。我们使用该模型来研究各种撞击体质量和成分，包括基于太阳系彗星和星际冰（使用 JWST）观测的那些质量和成分。我们发现即使是一个小的冲击器（右= 2.5 km）可导致大气化学发生显着的短期变化，包括 H ₂ O、CO 和 CO ₂丰度增加 >10 倍，以及更普遍的大气不透明度，以及几乎完全去除来自高层大气的可观察到的碳氢化合物，例如 CH ₄ 。这些影响随着大气 C/O 比和金属丰度的变化而变化。对于经历过重大/持续轰击的物体来说，可能会发生潜在的可观察到的变化，从而使全球大气化学受到影响。我们的工作表明，彗星撞击可以显着改变或污染热木星的大气成分/化学成分。这些变化有可能削弱/打破大气 C/O 比与相对于出生原行星盘关键雪线的行星形成位置之间的拟议联系。