Monday, September 26, 2022

Scientists observed a quasi-periodic fast-propagating (QFP) wave train in corona

The images were taken by the LASCO on board the SOHO.

Quasi-periodic fast-propagating (QFP) wave trains are usually observed in the low corona using extreme ultraviolet images. They can be classified into narrow and broad QFP wave trains propagating along and perpendicular to magnetic fields.

Both types are tightly associated with periodic pulsations in flares, but their excitation mechanisms are still an open question.

Scientists from the Yunnan Observatories of the Chinese Academy of Sciences have observed a QFP wave in the outer corona at the height of about two to four solar radii in the white-light images.

In the low corona eruption source region, the scientists discovered a magnetic breakout architecture made up of a sizable high-lying loop housing three low-lying loops. The reconnection took place between the two sides of low-lying loops, as opposed to the typical breakout reconnection between the middle low-lying and the high-lying big loops.

Prof. SHEN Yuandeng from the Yunnan Observatories of the Chinese Academy of Sciences said, “Such reconnection does not result in a coronal mass ejection in the outer corona, since the reconnection continuously generates new reconnected high-lying large loops so that the confining ability of the high-lying loop becomes more and more strong. Therefore, the eruption in the low corona should be failed.” 

The freshly generated, rejoined high-lying loops are likewise successively stretched and expanded due to this process, which can naturally ignite the observed QFP wave train due to the pulsed increase in outward magnetic and plasma pressures.

This work presents the first white-light imaging observation of QFP wave trains in the outer corona. It provides the detailed energy releasing process in the low corona magnetic reconnection that subsequently excited the observed QFP wave train.

Journal Reference:

  1. Yuandeng Shen et al. White-light QFP wave train and the associated failed breakout eruption. Astronomy & Astrophysics. DOI: 10.1051/0004-6361/202243924
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