发表机构
Florida Space Institute, University of Central Florida; Brigham Young University Department of Physics & Astronomy; Northern Arizona University; Space Telescope Science Institute（佛罗里达空间研究所，中佛罗里达大学; 杨百翰大学物理与天文学系; 北亚利桑那大学; 太空望远镜科学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过卫星动力学测量妊神星扁率，揭示其致密岩石核心与冰质地幔结构，表明此类内部构造在跨海王星矮行星中可能普遍存在。
AI 中文摘要
外太阳系中的冰冷矮行星是已知最神秘的星体之一，展现出从大气表面更新到可能的低温火山活动等各种活动。然而，对其内部结构的研究在很大程度上仍停留在理论层面，缺乏经验测量数据来指导我们的理解。其卫星的轨道提供了一种打破这一僵局的方法，直接探测矮行星的内部结构。在此，我们基于妊神星卫星系统的运动，对其内部结构进行了详细研究。通过将新的动力学模型拟合至二十年来精确的哈勃太空望远镜天体测量数据，我们同时测量了妊神星的动力学扁率$J_2$及其卫星的质量。我们对$J_2$测量结果的分析，结合掩星推导的形状模型，确凿地表明妊神星具有一个致密的岩石核心，其上覆盖着富含冰的地幔。然而，当前数据集尚不足以完全确定详细的内部结构（核心/地幔密度、两层与三层结构等）。我们确实发现模型略微偏好妊神星保留冻结的化石形状，但需要更多数据来统计确认这一点。未来对卫星系统的观测以及恒星掩星观测，将需要全面检验这一假设，并应大幅收紧对妊神星内部的约束。结合近期关于矮行星地球物理和地球化学演化的其他证据，我们的工作表明，致密岩石核心和地下海洋可能在跨海王星矮行星中普遍存在。
英文摘要
The icy dwarf planets in the outer solar system are among the most enigmatic bodies known, showing activity ranging from atmospheric resurfacing to possible cryovolcanism. Yet the study of their interiors remains largely theoretical, with few empirical measurements to guide our understanding. The orbits of their moons offer a way to break this deadlock, providing a direct probe of dwarf planet interiors. Here we present a detailed investigation of Haumea's interior derived from the motion of its satellite system. Fitting a new dynamical model to two decades of precise Hubble Space Telescope astrometry, we simultaneously measure Haumea's dynamical oblateness, $J_2$, and the masses of its satellites. Our analysis of the $J_2$ measurement combined with occultation-derived shape models conclusively shows that Haumea has a dense rocky core overlaid with an ice-rich mantle. However, the current dataset is not constraining enough to fully determine the detailed internal structure (core/mantle density, two-layer vs. three-layer, etc.). We do find a slight preference for models where Haumea retains a frozen-in fossil figure, but more data are needed to statistically confirm this. Future observations of the satellite system, as well as observations of stellar occultations, are needed to fully test this hypothesis and should substantially tighten constraints on Haumea's interior. Taken together with other recent evidence for geophysical and geochemical evolution of dwarf planets, our work shows that dense rocky cores and subsurface oceans are likely to be ubiquitous among the trans-Neptunian dwarf planets.
CommentsAccepted for publication in ApJL
