Felix Sainsbury-Martinez, Catherine Walsh, Greg Cooke
{"title":"The Impact of Icy Cometary 'Impacts' on Exoplanetary Atmospheres I: Tidally-Locked Terrestrial Exoplanets","authors":"Felix Sainsbury-Martinez, Catherine Walsh, Greg Cooke","doi":"arxiv-2409.11151","DOIUrl":null,"url":null,"abstract":"Impacts by rocky and icy bodies are thought to have played a key role in\nshaping the composition of solar system objects, including the Earth's\nhabitability. Hence, it is likely that they play a similar role in exoplanetary\nsystems. We investigate how an icy cometary impact affects the atmospheric\nchemistry, climate, and composition of an Earth-like, tidally-locked,\nterrestrial exoplanet, a prime target in the search for a habitable exoplanet\nbeyond our solar system. We couple a cometary impact model which includes\nthermal ablation and pressure driven breakup with the 3D Earth System Model\nWACCM6/CESM2, and use this model to investigate the effects of the water and\nthermal energy delivery associated with an $R=2.5$ km pure water ice cometary\nimpact on an Earth-like atmosphere. We find that water is the primary driver of\nlonger timescale changes to the atmospheric chemistry and composition by acting\nas a source of opacity, cloud ice, and atmospheric hydrogen/oxygen. The water\nopacity drives heating at $\\sim5\\times10^{-4}$ bar, and cooling below, due to a\ndecreased flux reaching the surface. The increase in atmospheric hydrogen and\noxygen also drives an increase in the abundance of hydrogen/oxygen rich\nmolecules, with the exception of ozone, whose column density decreases by\n$\\sim10\\%$. These atmospheric changes are potentially observable for $\\sim$ 1-2\nyears post-impact, particularly those associated with cloud ice scattering.\nThey also persist, albeit at a much reduced level, to our quasi-steady-state,\nsuggesting that sustained bombardment or multiple large impacts have the\npotential to shape the composition and habitability of terrestrial exoplanets.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"31 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - PHYS - Earth and Planetary Astrophysics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.11151","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Impacts by rocky and icy bodies are thought to have played a key role in
shaping the composition of solar system objects, including the Earth's
habitability. Hence, it is likely that they play a similar role in exoplanetary
systems. We investigate how an icy cometary impact affects the atmospheric
chemistry, climate, and composition of an Earth-like, tidally-locked,
terrestrial exoplanet, a prime target in the search for a habitable exoplanet
beyond our solar system. We couple a cometary impact model which includes
thermal ablation and pressure driven breakup with the 3D Earth System Model
WACCM6/CESM2, and use this model to investigate the effects of the water and
thermal energy delivery associated with an $R=2.5$ km pure water ice cometary
impact on an Earth-like atmosphere. We find that water is the primary driver of
longer timescale changes to the atmospheric chemistry and composition by acting
as a source of opacity, cloud ice, and atmospheric hydrogen/oxygen. The water
opacity drives heating at $\sim5\times10^{-4}$ bar, and cooling below, due to a
decreased flux reaching the surface. The increase in atmospheric hydrogen and
oxygen also drives an increase in the abundance of hydrogen/oxygen rich
molecules, with the exception of ozone, whose column density decreases by
$\sim10\%$. These atmospheric changes are potentially observable for $\sim$ 1-2
years post-impact, particularly those associated with cloud ice scattering.
They also persist, albeit at a much reduced level, to our quasi-steady-state,
suggesting that sustained bombardment or multiple large impacts have the
potential to shape the composition and habitability of terrestrial exoplanets.
岩石和冰体的撞击被认为在塑造太阳系天体的组成,包括地球的可居住性方面发挥了关键作用。因此,它们很可能在系外行星系统中扮演着类似的角色。我们研究了冰质彗星撞击如何影响一颗类地、潮汐锁定、陆地系外行星的大气化学、气候和成分,这颗系外行星是寻找太阳系外宜居系外行星的主要目标。我们将一个包含热烧蚀和压力驱动破裂的彗星撞击模型与三维地球系统模型WACCM6/CESM2结合起来,并利用该模型研究了与$R=2.5$ km纯水冰彗星撞击类地大气相关的水和热能传递的影响。我们发现,水作为不透明性、云冰和大气氢/氧的来源,是大气化学和成分发生较长时间变化的主要驱动力。由于到达地表的通量增加,水的不透明性推动了在 $\sim5\times10^{-4}$ bar 条件下的升温和在以下条件下的降温。大气中氢气和氧气的增加也推动了富氢/氧分子丰度的增加,但臭氧除外,它的柱密度降低了$\sim10\%$。这些大气变化有可能在撞击后1-2年内被观测到,特别是那些与云冰散射有关的变化。它们也会持续存在,尽管水平要低得多,直到我们的准稳态,这表明持续轰击或多次大型撞击有可能塑造陆地系外行星的组成和宜居性。