Protopapa Silvia, Raut Ujjwal, Wong Ian, Stansberry John, Villanueva Geronimo L, Cook Jason, Holler Bryan, Grundy William M, Brunetto Rosario, Cartwright Richard J, Mamo Bereket, Emery Joshua P, Parker Alex H, Guilbert-Lepoutre Aurelie, Pinilla-Alonso Noemi, Milam Stefanie N, Hammel Heidi B
Southwest Research Institute, Boulder, CO, USA.
Southwest Research Institute, San Antonio, TX, USA.
Nat Commun. 2024 Oct 1;15(1):8247. doi: 10.1038/s41467-024-51826-4.
Charon, Pluto's largest moon, has been extensively studied, with research focusing on its primitive composition and changes due to radiation and photolysis. However, spectral data have so far been limited to wavelengths below 2.5 μm, leaving key aspects unresolved. Here we present the detection of carbon dioxide (CO) and hydrogen peroxide (HO) on the surface of Charon's northern hemisphere, using JWST data. These detections add to the known chemical inventory that includes crystalline water ice, ammonia-bearing species, and tholin-like darkening constituents previously revealed by ground- and space-based observations. The HO presence indicates active radiolytic/photolytic processing of the water ice-rich surface by solar ultraviolet and interplanetary medium Lyman-α photons, solar wind, and galactic cosmic rays. Through spectral modeling of the surface, we show that the CO is present in pure crystalline form and, possibly, in intimately mixed states on the surface. Endogenically sourced subsurface CO exposed on the surface is likely the primary source of this component, with possible contributions from irradiation of hydrocarbons mixed with water ice, interfacial radiolysis between carbon deposits and water ice, and the implantation of energetic carbon ions from the solar wind and solar energetic particles.
冥王星最大的卫星卡戎已经得到了广泛研究，研究重点是其原始成分以及因辐射和光解作用而发生的变化。然而，到目前为止，光谱数据仅限于波长低于2.5微米的范围，关键问题仍未得到解决。在此，我们利用詹姆斯·韦布空间望远镜（JWST）的数据，展示了在卡戎北半球表面检测到二氧化碳（CO）和过氧化氢（HO）。这些检测结果增加了已知的化学物质清单，其中包括结晶水冰、含氨物质以及此前通过地基和天基观测揭示的类托林暗化成分。过氧化氢的存在表明富含水冰的表面受到太阳紫外线、行星际介质莱曼-α光子、太阳风和银河宇宙射线的活跃辐射分解/光解作用。通过对表面进行光谱建模，我们表明二氧化碳以纯晶体形式存在，并且可能在表面以紧密混合的状态存在。暴露在表面的内源性地下二氧化碳可能是该成分的主要来源，混合了水冰的碳氢化合物的辐照、碳沉积物与水冰之间的界面辐射分解以及来自太阳风和太阳高能粒子的高能碳离子注入也可能有贡献。
