发表机构
Florida Space Institute, University of Central Florida; Department of Physics, University of Central Florida; Space Telescope Science Institute; Instituto de Astrofísica de Andalucía; Department of Mechanical Engineering IIT Kanpur（佛罗里达空间研究所，中佛罗里达大学; 中佛罗里达大学物理系; 太空望远镜科学研究所; 安达卢西亚天体物理研究所; 坎普尔印度理工学院机械工程系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过重新分析恒星掩星与哈勃空间望远镜成像数据，测得夸欧尔卫星韦沃特的尺寸、三轴形状及低几何反照率，推测其冰质量分数不足100%，来源与冥王星、妊神星卫星不同。
AI 中文摘要
海王星外空间中矮行星大小天体的小型卫星被认为由巨型撞击产生，通常观测到其表面以明亮的水冰为主。本研究聚焦于夸欧尔的小型主卫星韦沃特（Weywot），在前期工作基础上，利用哈勃空间望远镜（HST）广角相机3号的11次轨道成像结果，重新分析了2023年6月韦沃特发生的恒星掩星事件。研究同时约束了韦沃特的旋转光变曲线及其独立的测光相位曲线，以此获得韦沃特尺寸、形状与几何反照率的更可靠测量结果。研究发现韦沃特的体积等效半径req为73±5 km，主轴a=82+5-3 km、b=73+5-3 km、c=65+8-12 km，呈三轴形状，该形状符合罗氏椭球 rubble-pile（ rubble-pile 意为碎石堆）模型的解释，仅需韦沃特当前半长轴处具备中等内部摩擦，且其形状可维持至夸欧尔的共转半径。此外，韦沃特的几何反照率pV为0.036+0.010-0.006，与阋神星（Eris）卫星狄丝诺米娅（Dysnomia）相近，但比冥王星（Pluto）的小型卫星及妊神星（Haumea）的卫星低一个数量级以上。研究推测这可能表明韦沃特的冰质量分数<100%，且其并非源自分化后的撞击前原天体的水冰幔层，而冥王星小型卫星及妊神星卫星则被认为源自该类幔层。
英文摘要
The small satellites of dwarf-planet size worlds in trans-Neptunian space are thought to be produced through giant impacts, and are typically observed to have bright water-ice-dominated surfaces. Here we focus on Quaoar's small primary satellite, Weywot. We build on previous work by re-analyzing the June 2023 stellar occultation by Weywot using results from 11 orbits of HST imaging with the Wide Field Camera 3. Weywot's rotational lightcurve was constrained along with its independent photometric phase curve, which we used to obtain more robust measurements of Weywot's size, shape, and geometric albedo. We found Weywot's volume-equivalent radius to be req = 73+-5 km, with principal axes a = 82+5-3 , b = 73+5-3, c = 65+8-12 km, indicating a triaxial shape. This shape is consistent with a Roche-ellipsoid rubble-pile interpretation requiring only moderate internal friction at Weywot's current semimajor axis, and Weywot can retain this shape down to Quaoar's co-rotation radius. We also found Weywot's geometric albedo to be quite low, pV = 0.036+0.010-0.006, akin to that of Eris's satellite Dysnomia, but over an order of magnitude lower than Pluto's minor satellites and Haumea's satellites. We propose this may indicate that Weywot's ice-mass fraction < 100%, and that Weywot is not sourced from the water-ice mantle of a differentiated pre-impact progenitor as suggested for Pluto's minor satellites and Haumea's satellites.
