发表机构
University of Colorado, Boulder; NASA Goddard Space Flight Center; Mullard Space Science Laboratory, University College London; Space Sciences Laboratory, University of California, Berkeley; University of California, Los Angeles; Physics Department, University of California, Berkeley; University of Michigan, Ann Arbor; Lunar and Planetary Laboratory, University of Arizona; University of Delaware; Smithsonian Astrophysical Observatory; University of Toulouse; Imperial College London; Harvard University; Johns Hopkins Applied Physics Laboratory; European Space Agency, ESTEC（科罗拉多大学博尔德分校; 美国宇航局戈达德太空飞行中心; 穆拉德空间科学实验室，伦敦大学学院; 加州大学伯克利分校空间科学实验室; 加州大学洛杉矶分校; 加州大学伯克利分校物理系; 密歇根大学安娜堡分校; 亚利桑那大学月球与行星实验室; 特拉华大学; 史密森尼天体物理台; 图卢兹大学; 帝国理工学院; 哈佛大学; 约翰斯·霍普金斯大学应用物理实验室; 欧洲空间局欧洲空间研究与技术中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究利用帕克太阳探测器和太阳轨道器，首次在近太阳处测量到类极冠冕洞太阳风的加速过程，发现其加速需额外能量，为太阳风演化模型提供了约束。
AI 中文摘要
原位测量在很大程度上仍无法约束快速极冠冕洞（PCH）太阳风的早期演化。2025年3月，帕克太阳探测器（Parker）在其9.86太阳半径（$R_\u2609$）的近日点飞掠时，测量到来自一个大型赤道冕洞（ECH）的外流，该外流也被太阳轨道器（Solar Orbiter）在1天文单位（au）及中间距离处（太阳轨道器也接近其近日点）测量到。在1au处，该流的特性与尤利西斯号（Ulysses）确定的PCH特性一致。帕克探测器对该流的测量是在远低于阿尔文表面的位置进行的，质子温度超过2MK，在约10$R_\u2609$处的速度仅为其渐近值的约60%。太阳轨道器的数据表明，加速过程在60$R_\u2609$处基本完成。观测到该流的球偏振波动从帕克探测器处的近横向小角度波动发展为太阳轨道器处的完全反转“切换backs”。将推断出的加速剖面与历史多普勒变暗测量结果对比表明，该流的低日冕加速与PCH流的加速类似。与之前的研究一致，这种加速所需的能量远多于观测到的热压力梯度所能提供的能量，其中大量的阿尔文波动能量（在帕克探测器处观测到）可能贡献了重要部分。这些观测为最快太阳风的径向演化模型提供了独特约束，表明这些风流在演化的最初几十个太阳半径范围内经历了渐进、稳定的加速。
英文摘要
The early evolution of fast polar coronal hole (PCH) solar wind remains largely unconstrained by in situ measurements. In March 2025, Parker Solar Probe (Parker) at its closest approach of 9.86 Solar Radii ($R_\odot$) measured outflow from a large equatorial coronal hole (ECH) which was also measured at 1\,au and at intermediate distances by Solar Orbiter (also near its perihelion). At 1\,au the stream properties are consistent with PCH properties established by Ulysses. The stream was measured by Parker substantially below the Alfvén surface, with proton temperatures in excess of 2\,MK and a speed at $\sim$10\,$R_\odot$ which was only $\sim$60\% of its asymptotic value. The Solar Orbiter data indicates that the acceleration is largely complete by 60~$R_{\odot}$. Spherically-polarized fluctuations in the stream are observed to develop from near-transverse and small-angle at Parker to full reversal ``switchbacks'' at Solar Orbiter. Comparison of the implied acceleration profile to historical doppler-dimming measurements suggests that the stream's low coronal acceleration is similar to that of PCH flows. Consistent with previous work, this acceleration requires significantly more energy than can be provided by the observed thermal pressure gradients, with a significant contribution likely from the abundant Alfvénic fluctuation energy observed at Parker. These observations provide unique constraints on models of the radial evolution of the fastest solar wind, and indicate that these wind streams experience gradual, steady acceleration over their first few tens of solar radii of evolution.
Comments21 pages, 4 figures, Under Review in ApJL, Comments Welcome
