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.
Polarimetric Tomography Applied to Synthetic Multi-Spacecraft White-Light Images: Observing Coronal Mass Ejections in 3D
UKRI – RAL Space, Rutherford Appleton Laboratory(英国研究委员会 - 拉尔夫空间部,鲁瑟福阿普尔顿实验室);Predictive Science Inc.(预测科学公司);Austrian Space Weather Office, GeoSphere Austria(奥地利空间天气办公室,地球圈奥地利);Department of Physics, University of Helsinki(赫尔辛基大学物理系);Department of Meteorology, University of Reading(雷丁大学气象系);Faculty of Geodesy, University of Zagreb(萨格勒布大学大地测量学院);Institute of Physics, University of Graz(格拉茨大学物理研究所);U.S. Naval Research Laboratory(美国海军研究实验室);The Johns Hopkins University Applied Physics Laboratory(约翰斯·霍普金斯大学应用物理实验室)
School of Mathematics and Statistics, University of St Andrews(圣安德鲁斯大学数学与统计学院);School of Physics and Astronomy, University of St Andrews(圣安德鲁斯大学物理与天文学院);Observatories of the Carnegie Institution for Science(卡内基科学研究所天文台)
Multi-wavelength synthesis of a flux rope-trapped mini-prominence eruption and post-flare coronal rain
Instituto de Astrofísica de Canarias(加那利天体物理研究所);Universidad de La Laguna(拉古纳大学);University of Helsinki(赫尔辛基大学);Leibniz-Institut für Astrophysik Potsdam (AIP)(波茨坦莱布尼茨天体物理研究所);NASA Goddard Space Flight Center(美国宇航局戈达德太空飞行中心);Northumbria University(诺森比亚大学)
JCMT POL-2 and ALMA polarimetric observations of 6000-100 au scales in the protostar B335: linking magnetic field and gas kinematics in observations and MHD simulations
Milne-Eddington inversions of the He I 10830 Å Stokes profiles: Influence of the Paschen-Back effect
Paschen-Back效应影响He I多重态在10830 μ m处的塞曼子能级,导致这些谱线塞曼分量的强度和位置发生变化。我们说明了这种效果的相关性,使用合成斯托克斯配置文件的He I 10830的多重线,并调查其对极化数据反演的影响。我们反演的特内里费岛红外偏振仪(TIP)在德国真空塔望远镜(VTT)获得的数据。我们比较的反演结果的基础上计算的合成配置文件和没有Paschen-Back效应被包括在内。我们发现,当考虑到不完整的Paschen-Back效应,平均16%的高场强值。我们还表明,这种效果是不是主要原因的面积不对称性所表现出的许多He I 10830斯托克斯V-配置文件。这表明在这些线的形成高度范围内速度和磁场梯度的重要性。
对Li I 6708 A品系的6个旋转相进行了分析,这些旋转相分布于HD 166473的整个旋转周期(9.5年)。磁场模型是根据(Mathys等人,20007)的极化测量值构建的。对于每个观察到的相位,还根据考虑塞曼磁分裂的Fe II 6147 A、6149 A和Pr III 6706.7 A谱线轮廓的模拟来估计磁场的模量。通过将观察到的Li I 6708 A曲线与假设Paschen-Back分裂计算的合成曲线拟合并根据Pr III 6706.7 A线曲线估计磁场特性,获得每个相中的锂丰度。
From simulations to observations of cool plasma: What we can learn from synthetic spectra
NASA Goddard Space Flight Center(NASA戈达德太空飞行中心);Leibniz-Institut für Astrophysik Potsdam (AIP)(波茨坦莱布尼茨天体物理研究所);Northumbria University(诺森比亚大学);European Space Agency (ESA), European Space Astronomy Centre (ESAC)(欧洲空间局(ESA)欧洲航天天文中心)