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Coronal mass ejections (CMEs) are one of the most energetic eruptions in the solar atmosphere, which can seriously influence our high-technology activities through damaging satellites, disrupting navigation systems, and overloading power grids. CMEs often exhibit a classical three-part structure when observed with white-light coronagraphs, including a bright front, dark cavity, and bright core, as shown in Figure 1. For several decades, the bright core and dark cavity have been regarded as the erupted prominence and magnetic flux rope, respectively. However, this traditional explanation is facing challenges.
Figure 1. The three-part structure of CMEs (Credit: LASCO)
After five years of study, solar physicists from Shandong University, George Mason University, Nanjing University and National Astronomical Observatories proposed a new explanation for the three-part structure of CMEs, and four papers have been published in the Astrophysical Journal since 2017. They employ the dual-viewpoint observations of the Solar Dynamics Observatory (SDO), Solar and Heliospheric Observatory (SOHO), and Solar-Terrestrial Relations Observatory (STEREO) as shown in Figure 2, and suggest that both the prominence and magnetic flux rope are responsible for the bright core, while the dark cavity corresponds to a low-density zone between the front and core. This new explanation has been examined through CMEs from both solar active and quiet-Sun regions, said the leading author Prof. Song Hongqiang at the Institute of Space Sciences, Shandong University.
Figure 2. Dual-viewpoint observations from the Earth and STEREO (Song et al. 2022)
The first Chinese comprehensive satellite for solar physics study, i.e., the Advanced Space-based Solar Observatory (ASO-S) is scheduled for launch in late 2022. One of its payloads is the Lyman-α Solar Telescope, which can observe the field-of-view gap between SDO and SOHO. Seamless observations and further studies of CME structure can be conducted combining these missions in the near future, Prof. Song added.
Links to the Papers
Hongqiang Song*, Leping Li, and Yao Chen, Toward a Unified Explanation for the Three-part Structure of Solar Coronal Mass Ejections, The Astrophysical Journal, Volume 933, Issue 1, article id. 68, 7 pp. (2022).
https://iopscience.iop.org/article/10.3847/1538-4357/ac7239
Hongqiang Song*, Jie Zhang, Leping Li, Ying Liu, Bei Zhu, Bing Wang, Ruisheng Zheng, and Yao Chen, The Structure of Solar Coronal Mass Ejections in the Extreme-ultraviolet Passbands, The Astrophysical Journal, Volume 887, Issue 2, article id. 124, 8 pp. (2019b).
https://iopscience.iop.org/article/10.3847/1538-4357/ab50b6
Hongqiang Song*, Jie Zhang, Xin Cheng, Leping Li, Yongzhi Tang, Bing Wang, Ruisheng Zheng, and Yao Chen, On the Nature of the Bright Core of Solar Coronal Mass Ejections, The Astrophysical Journal, Volume 883, Issue 1, article id. 43, 8 pp. (2019a).
https://iopscience.iop.org/article/10.3847/1538-4357/ab304c
Hongqiang Song*, Xin Cheng, Yao Chen, Jie Zhang, Bing Wang, Leping Li, Bo Li, Qiang Hu, and Gang Li, The Three-part Structure of a Filament-unrelated Solar Coronal Mass Ejection, The Astrophysical Journal, Volume 848, Issue 1, article id. 21, 7 pp. (2017).
https://iopscience.iop.org/article/10.3847/1538-4357/aa8d1a