PROPAGATING WAVES ALONG SPICULES
PROPAGATING WAVES ALONG SPICULES
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DOI：
10.1088/2041-8205/736/2/l24
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发表时间：
2011-06
期刊：
影响因子：
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通讯作者：
T. Okamoto;B. De Pontieu
中科院分区：
文献类型：
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作者：
T. Okamoto;B. De Pontieu
Alfvénic波被认为在日冕加热和太阳风加速中起着重要作用。在这里，我们调查的统计特性Alfvénic波沿着针状物（喷流，突出到日冕）在极冕洞使用高节奏的观测太阳光学望远镜板日之出。我们开发了一种自动检测针状体和高频波的技术。我们探测到89个针状体，发现（1）混合向上传播，向下传播，以及驻波（2）相速随高度增加而逐渐增大，（3）低海拔以上行波为主，高海拔以驻波为主;（4）各骨针的早期和晚期以驻波为主，中期以上行波为主;（5）在某些针状体中，我们发现波向上传播（从底部）向下（从顶部）在骨针中间形成驻波;振幅、周期和速度振幅的中值分别为55 km、45 s和7.4 km s-1。我们推测，向上传播的波产生的太阳表面附近（低于骨针）和向下传播的波是由反射（最初）向上传播的波在骨针顶部的过渡区。向上和向下传播的波的混合意味着利用这些波来执行针状环境的地震学需要仔细分析，并且可能存在问题。
Alfvénic waves are thought to play an important role in coronal heating and acceleration of solar wind. Here we investigate the statistical properties of Alfvénic waves along spicules (jets that protrude into the corona) in a polar coronal hole using high-cadence observations of the Solar Optical Telescope on board Hinode. We developed a technique for the automated detection of spicules and high-frequency waves. We detected 89 spicules and found (1) a mix of upward propagating, downward propagating, as well as standing waves (occurrence rates of 59%, 21%, and 20%, respectively); (2) the phase speed gradually increases with height; (3) upward waves dominant at lower altitudes, standing waves at higher altitudes; (4) standing waves dominant in the early and late phases of each spicule, while upward waves were dominant in the middle phase; (5) in some spicules, we find waves propagating upward (from the bottom) and downward (from the top) to form a standing wave in the middle of the spicule; and (6) the medians of the amplitude, period, and velocity amplitude were 55 km, 45 s, and 7.4 km s−1, respectively. We speculate that upward propagating waves are produced near the solar surface (below the spicule) and downward propagating waves are caused by reflection of (initially) upward propagating waves off the transition region at the spicule top. The mix of upward and downward propagating waves implies that exploiting these waves to perform seismology of the spicular environment requires careful analysis and may be problematic.