The magnetic field topology of the weak-lined T Tauri star V410 Tauri - New strategies for Zeeman-Doppler imaging
The magnetic field topology of the weak-lined T Tauri star V410 Tauri - New strategies for Zeeman-Doppler imaging
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弱线金牛座 T 星 V410 Tauri 的磁场拓扑 - 塞曼多普勒成像的新策略
DOI：
10.1051/0004-6361/201220215
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发表时间：
2012
影响因子：
6.5
通讯作者：
A. Kuenstler
中科院分区：
文献类型：
--
作者：
T. Carroll;K. G. Strassmeier;J. Rice;A. Kuenstler
我们提出了一个详细的温度和磁场调查的金牛座T星星V410 Tau通过同时多普勒和塞曼多普勒成像。此外，我们提出了一种新的基于奇异值分解（SVD）的线轮廓重建方法来提取弱极化线轮廓。线轮廓重建的关键特征之一是SVD线轮廓可在我们的塞曼多普勒成像代码iMap中进行辐射传输建模。该代码还利用了一个新的迭代正则化方案，这是独立的任何额外的表面约束。为了提供更高的稳定性，我们的反演策略的一个重要部分是反演斯托克斯I和斯托克斯V轮廓，以同时重建V410 Tau的温度和磁场表面分布。一个新的图像剪切分析也实现了允许搜索的图像和线轮廓失真引起的差分旋转的星星。我们获得的磁场结构V410头显示出良好的空间相关性与表面温度和冷极斑内的强磁场占主导地位。塞曼-多普勒地图展示了一个大规模组织的两极周围的极帽的形式扭曲的双极结构。磁场在极地区域内达到近2 kG的值，但在低纬度地区也存在较小的磁场。明显的非轴对称场结构和未检测到V410 Tau的差分旋转支持了潜在的$\alpha^2 $-型发电机的想法，这是预测为弱线金牛座T星。
We present a detailed temperature and magnetic investigation of the T Tauri star V410 Tau by means of a simultaneous Doppler- and Zeeman-Doppler Imaging. Moreover we introduce a new line profile reconstruction method based on a singular value decomposition (SVD) to extract the weak polarized line profiles. One of the key features of the line profile reconstruction is that the SVD line profiles are amenable to radiative transfer modeling within our Zeeman-Doppler Imaging code iMap. The code also utilizes a new iterative regularization scheme which is independent of any additional surface constraints. To provide more stability a vital part of our inversion strategy is the inversion of both Stokes I and Stokes V profiles to simultaneously reconstruct the temperature and magnetic field surface distribution of V410 Tau. A new image-shear analysis is also implemented to allow the search for image and line profile distortions induced by a differential rotation of the star. The magnetic field structure we obtain for V410 Tau shows a good spatial correlation with the surface temperature and is dominated by a strong field within the cool polar spot. The Zeeman-Doppler maps exhibit a large-scale organization of both polarities around the polar cap in the form of a twisted bipolar structure. The magnetic field reaches a value of almost 2 kG within the polar region but smaller fields are also present down to lower latitudes. The pronounced non-axisymmetric field structure and the non-detection of a differential rotation for V410 Tau supports the idea of an underlying $\alpha^2$-type dynamo, which is predicted for weak-lined T Tauri stars.