Menten Stephanie M, Sori Michael M, Bramson Ali M
Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, USA.
Nat Commun. 2022 Aug 9;13(1):4457. doi: 10.1038/s41467-022-31846-8.
Kuiper belt objects (KBOs) have diverse surface compositions, and the New Horizons mission to the Pluto-Charon system allows us to test hypotheses on the origin and evolution of these KBO surfaces. Previous work proposed that Charon's organic-rich north pole formed from radiolytically processed volatiles sourced from Pluto's escaping atmosphere. Here, we show an endogenic source of volatiles from Charon's interior is plausible. We calculate that cryovolcanic resurfacing released 1.29 × 10-3.47 × 10 kg of methane to Charon's surface from its interior. We modeled volatile transport and found the vast majority of this volcanically released methane migrates to Charon's poles, with deposition rates sufficient to be processed into the observed organic compounds. Irradiated methane products appear on similarly sized KBOs that do not orbit a Pluto-sized object to draw an escaping atmosphere from, so interior-sourced volatiles could be a common and important process across the Kuiper belt.
柯伊伯带天体（KBOs）具有多样的表面成分，“新视野号”对冥王星 - 卡戎系统的探测任务使我们能够检验关于这些柯伊伯带天体表面起源和演化的假设。此前的研究提出，卡戎富含有机物的北极是由冥王星逃逸大气层中经辐射分解处理的挥发物形成的。在此，我们表明卡戎内部存在挥发物的内源是合理的。我们计算得出，低温火山活动使卡戎内部向其表面释放了1.29×10⁻³至4.7×10千克的甲烷。我们对挥发物的迁移进行了建模，发现这种火山活动释放的甲烷绝大多数迁移到了卡戎的两极，其沉积速率足以将其加工成观测到的有机化合物。在没有环绕冥王星大小天体运行以获取逃逸大气层的类似大小柯伊伯带天体上也出现了辐照甲烷产物，因此内源挥发物可能是柯伊伯带普遍且重要的过程。
