Bertrand Tanguy, Forget François, Lellouch Emmanuel
Laboratoire d'Études Spatiales et d'Instrumentation en Astrophysique, Observatoire de Paris, Université Paris Sciences & Lettres, CNRS, Sorbonne Université, University of Paris Diderot, Sorbonne Paris Cité, Meudon 92195, France.
Laboratoire de Météorologie Dynamique, Institut Pierre-Simon Laplace, CNRS, Sorbonne Université, École Normale Supérieure, Université Paris Science et Lettres, Ecole Polytechnique, Institut Polytechnique de Paris, Paris 75005, France.
Proc Natl Acad Sci U S A. 2024 Aug 20;121(34):e2408226121. doi: 10.1073/pnas.2408226121. Epub 2024 Aug 12.
Triton and Pluto are believed to share a common origin, both forming initially in the Kuiper Belt but Triton being later captured by Neptune. Both objects display similar sizes, densities, and atmospheric and surface ice composition, with the presence of volatile ices N, CH, and CO. Yet their appearance, including their surface albedo and ice distribution strongly differ. What can explain these different appearances? A first disparity is that Triton is experiencing significant tidal heating due to its orbit around Neptune, with subsequent resurfacing and a relatively flat surface, while Pluto is not tidally activated and displays a pronounced topography. Here we present long-term volatile transport simulations of Pluto and Triton, using the same initial conditions and volatile inventory, but with the known orbit and rotation of each object. The model reproduces, to first order, the observed volatile ice surface distribution on Pluto and Triton. Our results unambiguously demonstrate that obliquity is the main driver of the differences in surface appearance and in climate properties on Pluto and Triton, and give further support to the hypothesis that both objects had a common origin followed by a different dynamical history.
海卫一和冥王星被认为有着共同的起源，二者最初都在柯伊伯带形成，但海卫一后来被海王星捕获。这两个天体大小、密度、大气及表面冰成分相似，都存在挥发性冰氮、甲烷和一氧化碳。然而它们的外观，包括表面反照率和冰的分布却有很大差异。如何解释这些不同的外观呢？第一个差异是，海卫一因其绕海王星的轨道而经历显著的潮汐加热，随后表面重新形成且相对平坦，而冥王星没有受到潮汐作用的激活，表面地形起伏明显。在此，我们利用相同的初始条件和挥发性物质存量，但结合每个天体已知的轨道和自转情况，对冥王星和海卫一进行了长期挥发性物质输运模拟。该模型初步再现了在冥王星和海卫一上观测到的挥发性冰表面分布。我们的结果明确表明，倾角是冥王星和海卫一表面外观及气候特性差异的主要驱动因素，并进一步支持了这一假设：这两个天体有着共同的起源，随后经历了不同的动力学历史。
