Solar prominences are large magnetic structures confining a cool and dense plasma in the hot solar corona. Typically, the prominence plasma is 100 times cooler and denser than its coronal surroundings. This phenomenon raises some important questions about the origin of the prominence plasma, and the energy and force equilibria which allow it to remain in the corona for a relatively long time.

Thanks to high spatial and temporal imaging and spectroscopic observations, many fine structures in the prominence can be revealed, including prominence bubble and dark upflow plumes. However, the nature of prominence bubbles remains controversial and the detailed formation mechanism of dark upflow plumes is not clear.

In a recent study published in Astronomy and astrophysics, Dr. WANG Jincheng, Prof. YAN Xiaoli and other researchers from Yunnan Observatories of the Chinese Academy of Sciences found that the large plumes are generated from the breakup of the prominence bubble triggered by an enhancement of thermal pressure.

Based on high spatial and temporal resolution Hα data from the New Vacuum Solar Telescope, and simultaneous observations from the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory-Ahead, the researchers studied the dynamic and thermal properties of two large plumes in a prominence on 2021 April 14.

According to the stereoscopic observation of prominence bubble, researchers found extremely powerful evidence to support that the bubble below the prominence was filled with hot and low-density plasma.

On the other hand, many evidences indicate that two large plumes originate from the same bubble, and are associated with the disruption of the bubble. The researchers found that the bubble expanded and took on a quasi-semicircular appearance before the occurrence of each large plume. And the emission intensity of extreme-ultra-violet (EUV) bands increases in the bubble during the bubble expanding.

Based on the analysis of these two large plume formations, the researchers established a model for bubble evolution and deduced the requirement for the formation of the large plume. They conclude that the bubble cannot keep its shape and begin to generate the large plumes as the bubble height exceeds half its width.

Contact:

WANG Jincheng, YNAO, CAS

wangjincheng@ynao.ac.cn