报告人： 张捷教授  美国乔治梅森大学

    时间：   周四下午（6月21日）下午2:00

    地点：   教学行政楼1514

    摘要：Solar eruptions, manifested as spectacular phenomena of erupting filaments, flares and CMEs, are sudden and impulsive energy release in the Sun’s corona. It is generally believed that solar eruptions are driven by a magnetic process, i.e, storing magnetic energy in core magnetic structures near and overlying polarity inversion lines and subsequently releasing the energy through magnetic reconnection and/or ideal magnetohydrodynamic instability. The core magnetic structure could be either a strongly sheared magnetic arcade or a magnetic flux rope. This talk is focused on the research work that addresses the origin or creation of core magnetic structures and their evolution leading to solar eruptions. The specific questions include (1) what is the key process of forming the eruption-prone magnetic structure: flux emergence, cancellation, shearing motion or diffusion? (2) how is a magnetic flux rope formed: bodily emergence, flux cancellation, or magnetic reconnection? (3) how does the core magnetic structure evolve in the corona in responding to the photospheric motion? In particular, a “collisional shearing” scenario is proposed to explain the causes of major solar eruptions. Collisional shearing occurs between non-conjugated polarities between two different bipoles.