Numerical Magnetohydrodynamic Experiments for Testing the Physical Mechanisms of Coronal Mass Ejections Acceleration
Numerical Magnetohydrodynamic Experiments for Testing the Physical Mechanisms of Coronal Mass Ejections Acceleration
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DOI：
10.1007/s11207-004-2568-7
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发表时间：
2004-11
期刊：
影响因子：
2.8
通讯作者：
S. Wu;T. X. Zhang;E. Tandberg-Hanssen;Yang Liu;Xueshang Feng;A. Tan
中科院分区：
文献类型：
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作者：
S. Wu;T. X. Zhang;E. Tandberg-Hanssen;Yang Liu;Xueshang Feng;A. Tan
对星载（LASCO/SOHO、Skylaband 太阳极大值任务）和地面（莫纳罗亚天文台）仪器观测的分析表明，存在两种类型的日冕物质抛射（CME）：快速日冕物质抛射和慢速日冕物质抛射。快速的日冕物质抛射以较高的初始速度开始，该速度或多或少保持恒定，而慢速的日冕物质抛射以较低的初始速度开始，但显示出逐渐加速。为了解释两种类型的日冕物质抛射之间的差异，Low和Zhang（2002）提出，这是由于与底层静止日珥相关的磁场初始拓扑的差异造成的，即正常的日珥配置将导致日冕物质抛射速度快，而反静止日珥配置将导致日冕物质抛射速度慢。在本文中，我们探索了一种不同的场景来解释快速和慢速日冕物质抛射的存在。仅假设静止日珥的逆拓扑，我们表明快速和慢速日冕物质抛射是由不同的物理过程引起的，这些物理过程负责日冕磁场的不稳定以及日冕物质抛射的启动和发射。我们使用 2.5 维、时间相关拖缆和通量绳磁流体动力学 (MHD) 模型（Wu 和Guo，1997）并研究了三个引发过程，即。 (1) 将磁通量注入磁通绳，从而产生额外的洛伦兹力，使拖缆不稳定并发射日冕物质抛射 (Wuet al., 1997, 1999)； (2)从磁通绳中排出等离子体并触发磁浮力，使磁通绳提升并发射日冕物质抛射； (3)向磁通绳引入额外的加热，从而模拟活动区域磁通绳伴随着耀斑以发射日冕物质抛射。我们提出了单独或以各种组合使用这三种驱动机制的 12 项数值测试。结果表明，快速和慢速日冕物质抛射都可以从经历这三种不同启动过程中的一种或多种的逆日珥配置中获得。
Analysis of observations from both space-borne (LASCO/SOHO,Skylaband Solar Maximum Mission) and ground-based (Mauna Loa Observatory) instruments show that there are two types of coronal mass ejections (CMEs), fast CMEs and slow CMEs. Fast CMEs start with a high initial speed, which remains more or less constant, while slow CMEs start with a low initial speed, but show a gradual acceleration. To explain the difference between the two types of CMEs, Low and Zhang (2002) proposed that it resulted from a difference in the initial topology of the magnetic fields associated with the underlying quiescent prominences, i.e., a normal prominence configuration will lead to a fast CME, while an inverse quiescent prominence results in a slow CME. In this paper we explore a different scenario to explain the existence of fast and slow CMEs. Postulating only an inverse topology for the quiescent prominences, we show that fast and slow CMEs result from different physical processes responsible for the destabilization of the coronal magnetic field and for the initiation and launching of the CME. We use a 2.5-D, time-dependent streamer and flux-rope magnetohydrodynamic (MHD) model (Wu and Guo, 1997) and investigate three initiation processes, viz. (1) injecting of magnetic flux into the flux-rope, thereby causing an additional Lorentz force that will destabilize the streamer and launch a CME (Wuet al., 1997, 1999); (2) draining of plasma from the flux-rope and triggering a magnetic buoyancy force that causes the flux-rope to lift and launch a CME; and (3) introducing additional heating into the flux-rope, thereby simulating an active-region flux-rope accompanied by a flare to launch a CME. We present 12 numerical tests using these three driving mechanisms either alone or in various combinations. The results show that both fast and slow CMEs can be obtained from an inverse prominence configuration subjected to one or more of these three different initiation processes.