Variations of the solar granulation motions with height using the GOLF/SoHO experiment
Variations of the solar granulation motions with height using the GOLF/SoHO experiment
复制标题
使用 GOLF/SoHO 实验观察太阳粒化运动随高度的变化
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
S. Mathur
中科院分区：
文献类型：
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作者：
S. Lefebvre;R. A. García;S. Jiménez;S. Turck;S. Mathur;S. Mathur
上下文。在1 MHz以下，日震速度测量的功率谱主要是对流运动(颗粒和超颗粒)的频谱，很难检测到低阶声波模式和重力模式。目标。我们试图更清楚地了解太阳颗粒化作为太阳大气观测高度和太阳第23周期间的磁活动的函数的行为。方法：研究方法。本文利用哈维型模型分析了11年的GOLF/SOHO速度时间序列的功率谱密度(PSD)，以刻画太阳振荡功率谱中对流运动的特征。我们研究了颗粒随太阳大气高度和太阳活动的演化。结果。我们首先证明了用洛伦兹分布来描述p模包络的传统方法不适用于高尔夫数据。为了对太阳光谱进行适当的建模，我们必须采用第二个洛伦兹轮廓。其次，我们发现，颗粒化明显地随着光球层的高度而演化，但并不随活动周期呈现任何显著的变化。
Context. Below 1 mHz, the power spectrum of helioseismic velocity measurements is dominated by the spectrum of convective motions (granulation and supergranulation) and it is difficult to detect the low-order acoustic modes and gravity modes. Aims. We attempt to understand more clearly the behavior of solar granulation as a function of observing height in the solar atmosphere and with magnetic activity during solar cycle 23. Methods. We analyze the Power Spectral Density (PSD) of eleven years of GOLF/SOHO velocity time series data using a Harvey-type model to characterize the properties of the convective motions in the solar oscillation power spectrum. We study the evolution of the granulation with both altitude in the solar atmosphere and solar activity. Results. We first demonstrate that the traditional use of a Lorentzian profile to describe the envelope of the p modes is unsuitable for GOLF data. To model properly the solar spectrum, we must instead adopt a second Lorentzian profile. Secondly, we show that the granulation clearly evolves with height in the photosphere but does not present any significant variation with the activity cycle.