Seminar by Chen Xing (Nanjing Univ. & Laboratoire de Physique des Plasmas, Ecole Polytechnique)
Title: Deciphering CME Initiation - Kinematics and Heating
Abstract:
Understanding the evolution of coronal mass ejection (CME) progenitors such as solar filaments and sigmoids is the key to forecasting the onset of solar eruptions and thus disastrous space weather. Observations show that CMEs frequently have an initiation process in few to tens of minutes preceding the eruption. In this process, CME progenitors slowly rise with a moderate acceleration and meanwhile appear as bright structures in high-temperature EUV passbands, yet, the physical origins of which remain elusive. Here, with a combination of observations and a thermal-magnetohydrodynamics simulation, we show that the hyperbolic flux tube (HFT) reconnection and the torus instability play important roles in the CME initiation. The slow rise of CME progenitors is triggered by a topological transition of the reconnection region from a bald patch to the HFT. The reconnection in the HFT not only drives the slow rise through the slingshot effect and its reconnection outflow, but also heats the CME progenitor through Ohmic dissipation. The torus instability, which triggers the CME eruption, onsets during the later stage of the initiation process and also promotes the slow rise. Our study reveals the nature of the whole CME initiation process, and poses a new challenge to various triggering mechanisms of CME eruptions other than the torus instability.
Where: The seminar can be followed in person in building 200B, room 02.18 or online at the following link:
https://eu.bbcollab.com/guest/6fc7259fc2ba4f29af721ccb6a19eefd
