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arXiv 1102.5296astro-ph.SRastro-ph.IMphysics.space-ph
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模拟活动区的扩散:量化输入电晕的能量

Modeling the Dispersal of an Active Region: Quantifying Energy Input into the Corona

Duncan H. Mackay, L. M. Green, Aad van Ballegooijen

摘要:

本文提出了一种直接从视线磁象观测资料模拟非线性无力场的新方法。该技术使用序列的磁直接作为较低的边界条件,以驱动日冕磁场的演变之间的连续无力平衡在很长一段时间。它是通过将其应用到MDI观测的一个衰减的活动区域,NOAA AR 8005。活动区域在其中央子午线通过周围的4天期间被建模。在这段时间里,由于小尺度对流单体的随机运动主导了活动区的扩散。通过对模型中磁能建立的研究,发现这种小尺度运动可以在$2.5-3 \times 10^{25}$以外的任何地方注入自由磁能$^{-1}$。大部分的能量存储在中心的活动区域在低电晕,低于30微米。4天后,建立的自由能是10%,相应的势场。这种能量积累足以解释活动区域内日冕温度下的辐射损失。因此,小尺度的对流运动在日冕的能量平衡中起着不可或缺的作用。由于SDO:HMI和SDO:AIA仪器的高分辨率、高节奏观测,这项新技术具有广泛的应用。

英文摘要:

In this paper a new technique for modeling non-linear force-free fields directly from line of sight magnetogram observations is presented. The technique uses sequences of magnetograms directly as lower boundary conditions to drive the evolution of coronal magnetic fields between successive force-free equilibria over long periods of time. It is illustrated by applying it to MDI observations of a decaying active region, NOAA AR 8005. The active region is modeled during a 4 day period around its central meridian passage. Over this time, the dispersal of the active region is dominated by random motions due to small scale convective cells. Through studying the build up of magnetic energy in the model, it is found that such small scale motions may inject anywhere from $2.5-3 \times 10^{25}$ erg s$^{-1}$ of free magnetic energy into the coronal field. Most of this energy is stored within the center of the active region in the low corona, below 30 Mm. After 4 days the build-up of free energy is 10% that of the corresponding potential field. This energy buildup, is sufficient to explain the radiative losses at coronal temperatures within the active region. Small scale convective motions therefore play an integral part in the energy balance of the corona. This new technique has wide ranging applications with the new high resolution, high cadence observations from the SDO:HMI and SDO:AIA instruments.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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