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arXiv 1401.0736astro-ph.SR
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类惯性射流何时以及如何获得动能?

When and how does a prominence-like jet gain kinetic energy?

Jiajia Liu, Yuming Wang, Rui Liu, Quanhao Zhang, Kai Liu, Chenglong Shen, S. Wang

摘要:

喷流是相当数量的等离子体从色球层或低日冕喷射到高日冕中,是一种常见的现象。通常,喷流是由增亮或耀斑触发的,它提供了推动等离子体向上的第一个驱动力。在这个过程中,磁重联被认为是将磁能转化为热能、非热能和动能的机制。然而,大多数喷流可能会达到一个不寻常的高度,并结束远晚于其相关的耀斑结束。这一事实意味着,即使在重联之后,也有另一种方式将磁能连续地转换为动能。上面描述的图片在社区中是众所周知的,但如何以及有多少磁能通过重联以外的方式释放仍然不清楚。通过对SDO/AIA和STEREO-A/EUVI观测到的类重联喷流的研究,发现重联后磁场结构的持续弛豫是喷流爬升的重要过程。通过弛豫获得的喷流动能是重联获得的喷流动能的1.6倍。由此产生的能量通量比局部日冕加热所需的通量大数百倍,这表明这种喷流是保持日冕热的可能来源。此外,在喷射过程中始终出现旋转运动。我们的分析表明,在重联过程中产生的扭转阿尔文波可能不是释放磁能和驱动喷流的唯一机制。

英文摘要:

A jet is a considerable amount of plasma being ejected from the chromosphere or lower corona into the higher corona and is a common phenomenon. Usually, a jet is triggered by a brightening or a flare, which provides the first driving force to push plasma upward. In this process, magnetic reconnection is thought to be the mechanism to convert magnetic energy into thermal, nonthermal, and kinetic energies. However, most jets could reach an unusual high altitude and end much later than the end of its associated flare. This fact implies that there is another way to continuously transfer magnetic energy into kinetic energy even after the reconnection. The picture described above is well known in the community, but how and how much magnetic energy is released through a way other than reconnection is still unclear. By studying a prominence-like jet observed by SDO/AIA and STEREO-A/EUVI, we find that the continuous relaxation of the post-reconnection magnetic field structure is an important process for a jet to climb up higher than it could through only reconnection. The kinetic energy of the jet gained through the relaxation is 1.6 times that gained from the reconnection. The resultant energy flux is hundreds of times larger than the flux required for the local coronal heating, suggesting that such jets are a possible source to keep the corona hot. Furthermore, rotational motions appear all the time during the jet. Our analysis suggests that torsional Alfvén waves induced during reconnection could not be the only mechanism to release magnetic energy and drive jets.

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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