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Stereoscopic coronal magnetic field modeling

立体日冕磁场建模

基本信息

批准号：
342658497
负责人：
Dr. Thomas Wiegelmann
金额：
--
依托单位：
Max-Planck-Institut für Sonnensystemforschung (MPS)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/342658497?language=en
关键词：
Stereoscopic coronal magnetic field modeling

项目摘要

In the project 'Stereoscopic coronal magnetic field modeling', we want to study magnetic fields in solar active regions. Since continuous and accurate measurements of coronal magnetic field are not available, two complementary approaches have been developed to obtain the 3D structure of coronal magnetic fields: stereoscopy and extrapolation of photospheric field measurements.The accuracy of both methods is constrained by the available observational data, e.g., the ability to identify corresponding loop structures in EUV-images from different vantage points, the angle between the observing spacecraft and measurement errors in photospheric vector magnetograms. We therefore developed a new model, called 'Stereoscopic-NonLinear Force-Free Field model (S-NLFFF)' where NLFFF extrapolations from photospheric data are constrained by coronal observations. The newly developed S-NLFFF code was successfully tested with synthetic data.Within the proposed project we plan to apply this new approach to observations from SDO and STEREO in order to derive the 3D coronal magnetic field structure with unprecedented high accuracy. In a later step we will generalize our model to use EUV-images from one vantage point (SDO) only. The corresponding code can be applied to all datasets after the launch of SDO in 2010. The implementation of the S-NLFFF will be made in both Cartesian and spherical coordinates for active regions and global models, respectively.Our NLFFF-optimization code allows naturally to constrain the model by additional observations, e.g., chromospheric vector magnetograms. It will be the first time that a NLFFF method will use vector data from two different layers, photosphere, respectively chromosphere and be constrained from observations in the corona.NLFFF models are strictly valid only in the active region solar corona, but not in the photosphere and the lower part of the chromosphere. For a meaningful modeling of these layers, the plasma pressure gradient and the gravity force have to be taken into account. A corresponding self-consistent magneto-hydro-static model was developed by our group. The projections of the reconstructed 3D magnetic field lines onto multi-wavelength coronal images can be used to specify the temperature, density and pressure along coronal loops. The self-consistent magneto-hydro-static approach then models these quantities in the entire computational domain.

在“立体日冕磁场建模”项目中，我们希望研究太阳活动区的磁场。由于日冕磁场的连续和精确测量是不可用的，两种互补的方法被发展来获得日冕磁场的三维结构：体视法和光球场测量的外推法。这两种方法的精度受到现有观测数据的限制，例如，从不同Vantage位置识别极紫外图像中相应环路结构的能力、观测航天器之间的角度以及光球矢量磁图中的测量误差。因此，我们开发了一个新的模型，称为“立体非线性无力场模型（S-NLFFF）”，其中NLFFF从光球数据外推受到日冕观测的约束。新开发的S-NLFFF程序已经成功地通过了模拟数据的测试，在这个项目中，我们计划将这种新方法应用于SDO和STEREO的观测，以获得前所未有的高精度的三维日冕磁场结构。在后面的步骤中，我们将推广我们的模型，仅使用来自一个Vantage位置（SDO）的EUV图像。在2010年SDO启动后，相应的代码可以应用于所有数据集。S-NLFFF的实现将分别在活动区域和全局模型的笛卡尔坐标和球面坐标中进行。我们的NLFFF优化代码自然允许通过额外的观察来约束模型，例如，色球矢量磁图这将是NLFFF方法第一次使用来自两个不同层的矢量数据，分别是光球层和色球层，并受到日冕观测的约束。NLFFF模型仅在活动区日冕中严格有效，而不是在光球层和色球层的下部。为了对这些层进行有意义的建模，必须考虑等离子体压力梯度和重力。本课题组建立了相应的自洽磁流体静力学模型。重建的三维磁力线在多波长冠状图像上的投影可以用来确定沿着冠环的温度、密度和压力。自洽的磁流体静力学方法，然后在整个计算域中的这些量的模型。