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arXiv · 2402.02375

Formation of a streamer blob via the merger of multiple plasma clumps below 2Rs

Haiyi Li·Zhenghua Huang·Kaiwen Deng·Hui Fu·Lidong Xia·Hongqiang Song·Ming Xiong·Hengyuan Wei·Youqian Qi·Chao Zhang
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Abstract

Context. Propagating streamer blobs could be an important source of disturbances in the solar wind. Direct observations on formation of streamer blobs could be a proxy for understanding the formation of small-scale structures and disturbances in the solar wind. Aims. We aim to investigate how a streamer blob is formed before it is observed in the outer corona. Methods. Usingspecialcoordinated-observationsfromSOHO/LASCO,GOES/SUVIandSDO/AIA, we study the precursors of a streamer blob as seen in the corona below 2.0 solar radii (Rs). Results. We found that the streamer blob was formed due to the gradual merging of three clumps of brightenings initiated from the lower corona at about 1.8Rs, which is likely driven by expansion of the loop system at the base of the streamer. The acceleration of the blob starts from 1.9Rs or lower. It propagates along the south flank of the streamer where an expanding elongated brightening occurs coincidently. Conclusions. Our observations demonstrate that formation of a streamer blob is a complex process. We suggest that the expansion of the loop results in a pinching-off flux-rope-like blob at the loop apex below 2Rs. When the blob moves outward, it can be transferred across the overlying loops through interchange/component magnetic reconnection and then is released into the open field system. When the blob moves toward open field lines, interchange magnetic reconnections might also occur, and that can accelerate the plasma blob intermittently whilst allow it to transfer across the open field lines. Such dynamics in a streamer blob might further trigger small-scale disturbances in the solar wind such as switchbacks in the inner heliosphere.

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Haiyi Li, Zhenghua Huang, Kaiwen Deng, Hui Fu, Lidong Xia, Hongqiang Song, Ming Xiong, Hengyuan Wei, Youqian Qi, Chao Zhang. 2024-02-04. Formation of a streamer blob via the merger of multiple plasma clumps below 2Rs. https://arxiv.org/abs/2402.02375

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