嵌套闭磁场日冕背景结构对触发CME特征的影响

在子午面内,研究具有嵌套闭磁场结构冕流背景对触发日冕物质抛射(CME)特征的影响.在冕流背景磁场结构内有三个小尺度的闭磁场结构,其中中间小尺度闭磁场结构的磁场方向和冕流整体偶极磁场方向相反.CME触发模型在这个小尺度闭磁场结构下方浮出,它具有同心圆形磁场结构,半径为a=0.1Rs(Rs为太阳半径);CME触发模型前半部分磁场方向和触发位置处小尺度闭磁场结构的磁场方向相反,与冕流整体偶极磁场方向相同.数值模拟结果表明,当CME触发模型中心等离子压力与边界压力之比m≥2时,上浮CME触发模型可以触发CME;当m＜2时,上浮CME触发模型不能触发CME,计算结论的误差小于1%. 

Influence of a Streamer Background With Nested Close Magnetic Structures on the Properties of CME Initiated From Its Bottom

The influence of a streamer background with nested close magnetic structures on the properties of CME initiated from its bottom is investigated in a solar meridian plane. In the streamer there contain three small-scale close magnetic field structures with the magnetic direction of the middle one opposite to that of the solar global dipole. A CME triggering model made up of cocircular magnetic field lines is taken to emerge from the solar equator at the inner boundary, where the middle small-scale close magnetic field structure locates, of the computational domain. The magnetic field direction in the front half of the CME triggering model with a radius a = OARs （Rs is solar radius） is opposite to that of the magnetic field line at its emerging position and same to that of the streamer global dipole. It is found from numerical simulation that: the CME triggering model, with a ratio of plasma pressure at its center and that at its edge m ≥ 2, can trigger a CME and can not when m 〈 2. The error for this numerical conclusion is less than 1%.