AI 中文总结
该研究分析太阳轨道器观测到的磁云过境期间的SEP中断事件，结合成像和磁场诊断揭示中断源于相邻通量管间粒子可及性的快速变化，磁云可维持SEP强度梯度。
AI 中文摘要
我们分析了太阳轨道器于2022年12月24日在0.93天文单位处观测到的一次脉冲式太阳高能粒子（SEP）事件，该事件在协调世界时约07:15至10:00期间表现出显著的强度中断。 pitch角分布显示，中断前存在近场对齐的粒子束，在中断开始时突然消失；同时，在约90°至180°的 pitch角范围内出现了弱的100-200 keV粒子成分，而在MeV能量范围内该 pitch角区间无类似增强。中断开始时，原位磁场或太阳风等离子体未发生突变。太阳成像将该SEP事件与来自致密源的喷流相关联。弹道反演映射结合势场源表面外推及准分离层代理诊断表明，太阳轨道器名义上与源区相连，但位于强连通性梯度附近，微小位移即可将连接切换至相邻开放场线。原位测量显示该事件发生在磁云过境期间，事件后期还出现了额外的中断。这些结果支持以下解释：中断反映了相邻通量管之间粒子可及性的快速变化，而磁云可能有助于维持它们之间陡峭的SEP强度梯度。
英文摘要
We analyze an impulsive solar energetic particle (SEP) event observed by Solar Orbiter at 0.93 au on 2022 December 24 that exhibits a pronounced intensity dropout between approximately 07:15 and 10:00 UT. Pitch-angle distributions show a near-field-aligned beam before the dropout, which disappears abruptly at the dropout onset. At the same time, a weak 100--200 keV component appears at pitch angles of about 90--180 degrees; no comparable enhancement over this pitch-angle range is present at MeV energies. The dropout onset is not accompanied by an abrupt change in the in situ magnetic field or solar wind plasma. Solar imaging associates the SEP event with a jet from a compact source. Ballistic back mapping, together with Potential Field Source Surface extrapolations and quasi-separatrix-layer proxy diagnostics, indicates that Solar Orbiter nominally connects to the source region, but lies close to strong connectivity gradients where small displacement may shift the connection to neighboring open field lines. The in situ measurements show that the event occurs during a magnetic-cloud passage and that additional dropouts occur later in the event. These results favor an interpretation in which the dropout reflects rapid changes in particle access between adjacent flux tubes, while the magnetic cloud may help preserve the sharp SEP intensity gradients between them.
Comments10 pages, 5 figures. Accepted version of the paper. Publisher typeset PDF is provided as ancillary file
Journal refApJL 1006, L48 (2026)
