Formation of a tiny flux rope in the center of an active region driven by magnetic flux emergence, convergence, and cancellation. (arXiv:2009.04082v2 [astro-ph.SR] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Zheng_R/0/1/0/all/0/1">Ruisheng Zheng</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_Y/0/1/0/all/0/1">Yao Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_B/0/1/0/all/0/1">Bing Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Song_H/0/1/0/all/0/1">Hongqiang Song</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cao_W/0/1/0/all/0/1">Wenda Cao</a>
Flux ropes are generally believed to be core structures of solar eruptions
that are significant for the space weather, but their formation mechanism
remains intensely debated. We report on the formation of a tiny flux rope
beneath clusters of active region loops on 2018 August 24. Combining the
high-quality multiwavelength observations from multiple instruments, we studied
the event in detail in the photosphere, chromosphere, and corona. In the source
region, the continual emergence of two positive polarities (P1 and P2) that
appeared as two pores (A and B)is unambiguous. Interestingly, P2 and Pore B
slowly approached P1 and Pore A, implying a magnetic flux convergence. During
the emergence and convergence, P1 and P2 successively interacted with a minor
negative polarity (N3) that emerged, which led to a continuous magnetic flux
cancellation. As a result, the overlying loops became much sheared and finally
evolved into a tiny twisted flux rope that was evidenced by a transient inverse
S-shaped sigmoid, the twisted filament threads with blueshift and redshift
signatures, and a hot channel. All the results show that the formation of the
tiny flux rope in the center of the active region was closely associated with
the continuous magnetic flux emergence, convergence, and cancellation in the
photosphere. Hence, we suggest that the magnetic flux emergence, convergence,
and cancellation are crucial for the formation of the tiny flux rope.
Flux ropes are generally believed to be core structures of solar eruptions
that are significant for the space weather, but their formation mechanism
remains intensely debated. We report on the formation of a tiny flux rope
beneath clusters of active region loops on 2018 August 24. Combining the
high-quality multiwavelength observations from multiple instruments, we studied
the event in detail in the photosphere, chromosphere, and corona. In the source
region, the continual emergence of two positive polarities (P1 and P2) that
appeared as two pores (A and B)is unambiguous. Interestingly, P2 and Pore B
slowly approached P1 and Pore A, implying a magnetic flux convergence. During
the emergence and convergence, P1 and P2 successively interacted with a minor
negative polarity (N3) that emerged, which led to a continuous magnetic flux
cancellation. As a result, the overlying loops became much sheared and finally
evolved into a tiny twisted flux rope that was evidenced by a transient inverse
S-shaped sigmoid, the twisted filament threads with blueshift and redshift
signatures, and a hot channel. All the results show that the formation of the
tiny flux rope in the center of the active region was closely associated with
the continuous magnetic flux emergence, convergence, and cancellation in the
photosphere. Hence, we suggest that the magnetic flux emergence, convergence,
and cancellation are crucial for the formation of the tiny flux rope.
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