Alfvenic resonances on solar spicules
Alfvenic resonances on solar spicules
复制标题
太阳针状体上的阿尔芬共振
DOI：
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发表时间：
1984
期刊：
影响因子：
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通讯作者：
J. V. Hollweg
中科院分区：
文献类型：
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作者：
A. Sterling;J. V. Hollweg
结果表明，太阳针叶的扭转和加热可能是由阿尔芬波从下方进入针叶而产生的。针状体被视为阿尔芬速度恒定的区域，它的边界在阿尔芬速度高得多的区域(日冕)之上，阿尔芬速度指数级增长的区域(光球层和色球)之下。它展示了针状物如何起到谐振腔的作用。分析确定，在一定的共振频率下，波在腔体中的传输将得到增强。在合理的针刺参数下，假设针刺的阻尼值较大，则可在针刺上诱发约20-30公里/S的扭转速度。结果表明，阿尔芬波是通过其能量向更高波数的湍动级联消散的。结果表明，波可以将针状体加热到观测到的温度。进一步认为，能量的持续输入可以解释为什么H-α针状体褪色，因为预测的加热速度足以将针状体加热到氢完全电离的温度，因此H-α针状体可能演化为EUV针状体。
It is suggested that twisting and heating of solar spicules can be produced by Alfven waves which enter the spicule from below. The spicule is treated as a region of constant Alfven speed which is bounded above by a region of much higher Alfven speed (the corona) and below by a region of exponentially increasing Alfven speed (the photosphere and chromosphere). It is shown how the spicule can act as a resonant cavity. The transmission of the waves into the cavity is analytically determined to be enhanced at certain resonant frequencies. With reasonable spicule parameters, and assuming the spicule damping to be moderately large, it is found that twisting velocities of approximately 20-30 km/s can be induced on the spicule. It is suggested that the Alfven waves are dissipated via a turbulent cascade of their energy to higher wavenumbers. It is shown that the waves can thereby heat the spicules to the observed temperatures. It is further suggested that the continued input of energy can explain why H-alpha spicules fade, since the predicted heating rate is sufficient to heat the spicules to temperatures at which the hydrogen is fully ionized; thus H-alpha spicules may evolve into EUV spicules.