Slow magnetoacoustic waves in a static background provide a seismological tool to probe the solar atmosphere in the analytic frame. By analyzing the spatiotemporal variation of the electron number density of plume structure in coronal holes above the limb for a given temperature, we find that the density perturbations accelerate with supersonic speeds in the distance range from 1.02 to 1.23 solar radii. We interpret them as slow magnetoacoustic waves propagating at about the sound speed with accelerating subsonic flows. The average sonic height of the subsonic flows is calculated to be 1.27 solar radii. The mass flux of the subsonic flows is estimated to be 44.1% relative to the global solar wind. Hence, the subsonic flow is likely to be the nascent solar wind. In other words, the evolution of the nascent solar wind in plumes at the low corona is quantified for the first time from imaging observations. Based on the interpretation, propagating density perturbations present in plu...

中文翻译：

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日冕孔羽中的加速和超音速密度波动：新生太阳风的特征

静态背景下的慢磁声波提供了一种地震学工具，可以在分析框架中探测太阳大气。通过分析给定温度下肢体上方冠状孔内羽状结构中电子结构密度的时空变化，我们发现密度扰动以超音速在太阳半径1.02至1.23范围内加速。我们将它们解释为以大约声速传播并随着亚音速流加速而传播的慢磁声波。亚音速流的平均音高经计算为1.27太阳半径。相对于全球太阳风，亚音速流的质量通量估计为44.1％。因此，亚音速流很可能是新生的太阳风。换一种说法，在低电晕条件下羽流中初生的太阳风的演变首次通过成像观测得以量化。根据该解释，存在于介质中的传播密度扰动。