The Scientific Committee on Solar-Terrestrial Physics (SCOSTEP) is pleased to announce that the SCOSTEP Distinguished Scientist Award 2024 Ceremony and the 25th SCOSTEP/PRESTO Online Seminar by Dr. Jie Zhang will be held online on 8 November 2024.
Flares and coronal mass ejections (CMEs) are the two largest energetic phenomena originating in the Sun’s atmosphere. They are different in observations: flares are manifested as a spontaneous release of EM radiations in almost all wavelengths through the acceleration of non-thermal particles and plasma heating, while CMEs, equally energetic, are observed as the eruption and ejection of a large-scale organized magnetic structure into the outer corona. In this talk, the debate in the 1990s on the so-called “solar flare myth” will be reflected upon, which initiated the paradigm shift on the cause of space weather from a flare-centered view to a CME-centered view. Secondly, a comprehensive overview of our improved understanding of the relationship between flares and CMEs will be made.
Thanks to the advancement in observations made by a series of modern space observatories, including SOHO, STEREO and SDO, it has been found that mostly the energetic process of a flare (e.g., the increase of X-ray flux) and the accompanying CME (e.g., the increase of the CME velocity) is highly synchronized in time.
They are intimately coupled in the energy release process; thus, they should be collectively called a solar eruption. On the other hand, the Sun shows a zoology of the phenomena, as they can also occur independently from each other, namely confined flares and “stealthy” CMEs, respectively. The physical causes of the coupling and the diversity will be discussed in this talk. Lastly, how and what solar eruptions affect the geo-space, i.e., the Sun-to-Earth chain activities, will be presented, with a focus on the in-situ solar wind properties from two types of CMEs, i.e., originated from active regions versus those from quiescent regions.
Image by NASA-Imagery from Pixabay
