DKIST揭示MHD预测的亚50公里光球涡旋
DKIST unveils MHD-predicted sub-50 km photospheric vortices
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- Universidad Nacional de Colombia（哥伦比亚国立大学）
- Max-Planck-Institut für Sonnensystemforschung（马克斯·普朗克太阳系统研究所）
- National Solar Observatory（国家太阳观测台）
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中文总结 AI 辅助
本研究利用DKIST高分辨率观测首次直接探测到MHD预测的亚50公里光球涡旋，共识别201次，中位直径38.6公里，证实了模拟预测并开启小尺度对流动力学新观测窗口。
中文摘要 AI 辅助
太阳涡旋是旋转的等离子体结构，在能量和磁螺度从光球层向色球层及日冕传输中起着关键作用。尽管数值模拟预测存在直径为50至100公里的小尺度光球涡旋，但迄今尚未有直接的观测证据报道，主要原因是以往仪器的空间分辨率有限。在此，我们分析了使用4米丹尼尔·井上太阳望远镜（DKIST）在416纳米波长获得的高分辨率观测数据，其空间分辨率为12.3公里。利用傅里叶局部相关跟踪和涡旋强度判据（λ_ci），我们在143帧重建图像序列中识别出201次涡旋探测，覆盖约3.2分钟的时间跨度，视场为4.92×4.13兆米。观测覆盖了一个包含孔隙状磁聚集的光球谱斑区域。探测到的涡旋中位等效直径为38.6公里，平均直径为39.5±3.3公里。几乎所有探测到的涡旋都小于50公里，因此属于磁流体动力学模拟预测但此前从未观测到的亚颗粒尺度范围。中位涡旋周期τ_ci=37.3秒，满足MURaM模拟建立的τ_ci<100秒的判据。顺行旋转（53.7%）与逆行旋转（46.3%）之间未发现统计学显著偏好，这与科里奥利力在亚颗粒尺度上影响可忽略不计的结论一致。这些结果证明了DKIST解析最先进磁对流模拟所预测的光球对流涡旋群体的独特能力，为小尺度太阳对流动力学开辟了新的观测窗口。
英文摘要
Solar vortices are rotating plasma structures that play a key role in the transport of energy and magnetic helicity from the photosphere to the chromosphere and corona. While numerical simulations predict the existence of small-scale photospheric vortices with diameters of $50$--$100$ km, no direct observational evidence has been reported to date, primarily because of the limited spatial resolution of previous instrumentation. Here, we analyze high-resolution observations obtained with the 4-meter Daniel K. Inouye Solar Telescope (DKIST) at 416 nm, with a spatial resolution of 12.3 km. Using Fourier local correlation tracking and the swirling strength criterion ($λ_{\rm ci}$), we identify 201 vortex detections across a sequence of 143 reconstructed frames, spanning approximately 3.2 minutes, within a field of view of $4.92 \times 4.13$ Mm. The observations cover a photospheric plage region containing pore-like magnetic concentrations. The detected vortices have a median equivalent diameter of 38.6 km and a mean diameter of $39.5 \pm 3.3$ km. Virtually all detections are smaller than 50 km and therefore fall within the subgranular regime predicted by magnetohydrodynamic simulations but never previously observed. The median swirling period, $τ_{\rm ci}=37.3$ s, satisfies the $τ_{\rm ci}<100$ s criterion established by MURaM simulations. No statistically significant preference is found for prograde rotation (53.7\%) over retrograde rotation (46.3\%), consistent with the negligible influence of the Coriolis force at subgranular scales. These results demonstrate the unique capability of DKIST to resolve the population of photospheric convective vortices predicted by state-of-the-art magnetoconvection simulations, opening a new observational window into small-scale solar convective dynamics.
