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arXiv 0903.3158astro-ph.SR
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特内里费岛红外线偏振仪观测的宁静太阳互联网的磁通量

The magnetic flux of the quiet Sun internetwork as observed with the Tenerife Infrared Polarimeter

C. A. R. Beck, R. Rezaei

摘要:

最近用HINODE卫星进行的观测发现,在网间平静的太阳中存在丰富的水平磁场。我们比较的结果与地面观测的水平场。我们获得了30秒积分的数据,安静的太阳在光盘中心在一个非常好的看到。这些数据的偏振均方根噪声约为连续谱强度的2 × 10^-4。低噪声水平允许光谱的反转。我们比较了反演结果与代理的磁通量的确定。我们证实了水平场的存在,在安静的太阳互联网,与空隙的一些颗粒范围内几乎为零的线性偏振信号。圆偏振信号中的空洞仅具有颗粒尺度。超过60%的表面显示出高于均方根噪声水平四倍的偏振信号。我们发现,总磁通量包含在更倾向于水平场(γ> 45度)是由一个小的因素,约2比倾斜较小的领域。通量测定的代理人被认为是遭受大气的热力学状态的强烈影响。我们认为,地基红外数据和卫星可见光数据之间的水平与横向通量的比值的差异是由于各自的谱线的形成高度不同。我们要注意的是,磁通量的真实量不能直接从光谱中导出。对于纯粹的水平通量,需要其垂直延伸,必须通过以观测谱作为边界条件的显式建模来估计,或者必须从MHD模拟中获得。

英文摘要:

Recent observations with the HINODE satellite have found abundant horizontal magnetic fields in the internetwork quiet Sun. We compare the results on the horizontal fields with ground-based observations. We obtained 30 sec-integrated data of quiet Sun on disc centre during a period of very good seeing. The data have a rms noise in polarization of around 2 10^-4 of the continuum intensity. The low noise level allowed for an inversion of the spectra. We compare the inversion results with proxies for the determination of magnetic flux. We confirm the presence of the horizontal fields in the quiet Sun internetwork, with voids of some granules extent of nearly zero linear polarization signal. Voids in the circular polarization signal are only of granular scale. More than 60 % of the surface show polarization signals above four times the rms noise level. We find that the total magnetic flux contained in the more inclined to horizontal fields (gamma > 45 deg) is smaller by a factor of around 2 than that of the less inclined fields. The proxies for flux determination are seen to suffer from a strong influence of the thermodynamic state of the atmosphere. We suggest that the difference of the ratio of horizontal to transversal flux between the ground-based infrared data and the satellite-based visible data is due to the different formation heights of the respective spectral lines. We caution that the true amount of magnetic flux cannot be derived directly from the spectra. For purely horizontal flux, one would need its vertical extension that has to estimated by an explicit modeling with the observed spectra as boundary conditions, or has to be taken from MHD simulations.

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