In a recent study, Prof. DENG Linhua from Yunnan Observatories of Chinese Academy of Sciences, in collaboration with Prof. WANG Feng and LIN Jiaqi from Guangzhou University, investigated the temporal and spatial behaviors of the Coronal Mass Ejections (CMEs) at high and low latitudes. The correlation and the phase relationships between the occurrence rate of the CMEs, the Coronal Brightness Index (CBI) and the 10.7-cm solar radio flux were also studied. This work was accepted by The Astrophysical Journal.

CMEs are large expulsions of magnetized plasma from the Sun, which attract considerable attention as they have far reaching consequences in solar, coronal and interplanetary physics. Previous studies found some differences between the high-latitude and low-latitude CMEs. The former is closely related to polar crown filaments, while the latter mainly to sunspots. That is, there exist differences in temporal and spatial behaviors between them.

By comparing the relationship between the occurrence rate and solar activity indicators, researchers found that the high-latitude occurrence rate has a relatively stronger correlation relationship with high-latitude CBI than solar radio flux (lower coronal activity). However, the situation for the low-latitude occurrence rate is not identical. The result indicates that the process of magnetic energy accumulation and dissipation is from the lower to the upper atmosphere of the Sun.

Researchers also found that the correlation relationships of the occurrence rate, solar radio flux and brightness index are stronger in cycle 24 than cycle 23. The difference in the correlation degree during different solar cycles might be associated with the real differences in the behaviors of strong and weak photospheric magnetic fields in these two cycles.

This work can be helpful for understanding of how magnetic energy is built up, stored and released in magnetic flux systems, as well as the origin and the formation process of CMEs, which are essential for solar physicists to reveal magnetic activity cycle and predict catastrophic space weather.

Contact:
DENG Linhua
Yunnan Observatories, CAS
Email: lhdeng@ynao.ac.cn