Recently, Professor YAN Xiaoli from the Fuxian Lake Solar Observation and Research Base of the Yunnan Astronomical Observatory, in collaboration with Professor CHEN Pengfei from Nanjing University, Professor XIA Chun from Yunnan University, and colleagues, conducted a detailed study on the dynamic evolution of solar prominences at the solar limb. By combining high-resolution observational data of solar limb prominences obtained from the 1-meter New Vacuum Solar Telescope (NVST) with spectral observations from the IRIS satellite, the team discovered distinct dynamic characteristics in different regions of solar prominences, which helped to explain the origin of the counterstreaming flow within prominences. The research was recently published in The Astrophysical Journal.

Solar prominences are one of the most spectacular active structures in the solar atmosphere, with various forms such as fence-like, cloud-like, flame-like, and arch-like shapes. Generally, larger prominences comprise a long central body (spine), several legs (referred to as barbs on the solar surface), and a cavity at the bottom (bubbles). Both the central body and the legs are made up of numerous fine threads. Doppler velocity observations have shown that counterstreaming flows exist within these threads. However, the origin of these bidirectional flows—first identified in 1998—has remained a subject of debate.

To investigate the origin of bidirectional flows, the team utilized NVST high-resolution observations of solar limb prominences and conducted a detailed study on their dynamic evolution. The study found that the upper part of the prominence’s spine exhibits an 83-minute oscillation, while the middle part of the spine shows significant counterstreaming flow with a velocity of approximately 10-20 kilometers per second. The lower part of the spine experiences intermittent material injections. 

These material injections occur in two ways: one involves the injection of material into the lower part of the prominence as the plume rises, and the other is driven by magnetic tornados from the legs of the prominence, which transport material into the lower part. These oscillations and material flows, mixed together, contribute to the ubiquitous counterstreaming flow present throughout the prominence.

The research was supported by the National Natural Science Foundation of China’s Distinguished Young Scholar Fund, the Strategic Priority Research Program of the Chinese Academy of Sciences, and the Yunnan Key Laboratory of Solar Physics and Space Science.

Figure 1: (a1): The prominence observed by the NVST. (a2-c2): the longitudinal oscillation of the middle part of the prominence. (a3-c3):the transverse oscillation of the prominence spine. Image by YAN.

Contact:
YAN Xiaoli
Yunnan Observatories , CAS
Email: yanxl@ynao.ac.cn