Intensity contrast from MHD simulations and HINODE observations
Intensity contrast from MHD simulations and HINODE observations
复制标题
MHD 模拟和 HINODE 观测的强度对比
DOI：
10.1051/0004-6361/201015582
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发表时间：
2011
影响因子：
6.5
通讯作者：
Afram N
中科院分区：
文献类型：
--
作者：
Afram N
背景小尺度磁性元素覆盖的太阳表面积的变化被认为会导致太阳光谱辐照度的长期变化，这对于确定对地球气候的影响是重要的。目的通过对太阳大气的三维MHD模拟，得出小尺度磁性元素对总辐照度和光谱辐照度的影响。这些计算是必要的，因为小尺度通量管对比度的测量限于几个波长，并且受到散射光和仪器散焦的影响，即使对于空间观测也是如此。方法为了检验对比度计算，我们将模拟得到的RMS对比度与安装在Hinode卫星上的太阳光学望远镜(SOT)上的宽带滤光片成像器获得的RMS对比度进行比较，并分析中心到肢体的变化(CLV)。三维MHD模拟包括对流和磁通量管之间的相互作用。它们是通过假定非灰色辐射传输并使用MURaM代码来执行的。模拟的垂直平均磁场分别为0G、50G和200G。用光谱综合程序ATLAS9计算了出射强度，并将其与理论上的点扩散函数进行卷积，以考虑观测光学系统的特性。结果在可见连续谱带内，模拟的强度分布与观测的强度分布符合得很好。CN和G-Band的一致性较差。对模拟的分析揭示了一种潜在的更真实的中心到肢体行为，而不是基于一维模型大气的计算。结论我们得出结论，从三维MHD模拟开始，是一种强大的方法，可以获得宽波长覆盖和太阳盘面上不同位置的强度对比度。这也为将来计算光斑和网络对比度作为磁通量的函数铺平了道路。
ContextChanges in the solar surface area, which is covered by small-scale magnetic elements, are thought to cause long-term changes in the solar spectral irradiance, which are important for determining the impact on Earth’s climate.AimsTo study the effect of small-scale magnetic elements on the total and spectral irradiance, we derive their contrasts from 3-D MHD simulations of the solar atmosphere. These calculations are necessary because measurements of small-scale flux tube contrasts are confined to a few wavelengths and affected by scattered light and instrument defocus, even for space observations.MethodsTo test the contrast calculations, we compare rms contrasts from simulations with those obtained with the broad-band filter imager mounted on the Solar Optical Telescope (SOT) onboard the Hinode satellite and also analyse centre-to-limb variations (CLV). The 3-D MHD simulations include the interaction between convection and magnetic flux tubes. They are performed by assuming non-grey radiative transfer and using theMURaMcode. The simulations have an average vertical magnetic field of 0 G, 50 G, and 200 G. Emergent intensities are calculated with the spectral synthesis code ATLAS9 and are convolved with a theoretical point-spread function to account for the properties of the observations’ optical system.ResultsWe find reasonable agreement between simulated and observed intensity distributions in the visible continuum bands. Agreement is poorer for the CN and G-bands. The analysis of the simulations uncovers a potentially more realistic centre-to-limb behaviour than calculations based on 1-D model atmospheres.ConclusionsWe conclude that starting from 3-D MHD simulations represents a powerful approach to obtaining intensity contrasts for a wide wavelength coverage and different positions across on the solar disk. This also paves the way for future calculations of facular and network contrast as a function of magnetic fluxes.
影响因子：
2.8
作者：
Kosugi, T.;Matsuzaki, K.;Golub, L.
通讯作者：
Golub, L.
影响因子：
8.6
作者：
Marsh, ND;Svensmark, H
通讯作者：
Svensmark, H
从日出测量的近紫外线中安静的太阳强度对比
DOI：
10.1088/2041-8205/723/2/l154
发表时间：
2010
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
J. Hirzberger;A. Feller;T. Riethmüller;M. Schüssler;J. Borrero;N. Afram;Y. Unruh;S. Berdyugina;A. Gandorfer;S. Solanki;P. Barthol;J. Bonet;V. Martínez Pillet;T. Berkefeld;M. Knölker;W. Schmidt;A. Title
通讯作者：
A. Title