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arXiv 1610.09282astro-ph.SR
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恒星光谱的合成偏振光谱

Synthetic polarimetric spectra from stellar prominences

T. Felipe, M. J. Martínez González, A. Asensio Ramos

摘要:

在快速旋转的恒星中探测到的恒星磁场可以作为冷恒星日冕中磁性的探测器。我们已经合成的斯托克斯配置文件中产生的He I 10830和5876 A三胞胎在日珥围绕恒星旋转的时间演化。合成进行了HAZEL代码使用云模型,其中的突出的特点是位于一个固定的纬度和高度的板。它解释了散射极化和塞曼和汉勒效应。分析了几种不同日珥磁场强度和方向的情况。结果表明,当日珥在恒星盘外时,辐射特征在剖面上漂移。当日珥遮蔽恒星时,强度轮廓显示出吸收。由日珥引起的散射产生斯托克斯Q和U分布中的线偏振信号,当存在磁场时,该线偏振信号被汉勒效应修改。由于塞曼效应,当沿视线的磁场不为零时,Stokes V剖面显示具有非常低幅度的信号。估计的线偏振信号可能会被未来的分光偏振计MIRADAS检测到,将被附加到GTC望远镜。

英文摘要:

Stellar prominences detected in rapidly rotating stars serve as probes of the magnetism in the corona of cool stars. We have synthesized the temporal evolution of the Stokes profiles generated in the He I 10830 and 5876 A triplets during the rotation of a prominence around a star. The synthesis was performed with the HAZEL code using a cloud model in which the prominence is characterized by a slab located at a fixed latitude and height. It accounts for the scattering polarization and Zeeman and Hanle effects. Several cases with different prominence magnetic field strengths and orientations have been analyzed. The results show an emission feature that drifts across the profile while the prominence is out of the stellar disk. When the prominence eclipses the star, the intensity profile shows an absorption. The scattering induced by the prominence generates linear polarization signals in Stokes Q and U profiles, which are modified by the Hanle effect when a magnetic field is present. Due to the Zeeman effect, Stokes V profiles show a signal with very low amplitude when the magnetic field along the line-of-sight is different from zero. The estimated linear polarization signals could potentially be detected with the future spectropolarimeter MIRADAS, to be attached to GTC telescope.

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