H I Ly- $α$、Mg II K、Ca II K、Ca I 4227等强共振线在太阳强度谱中具有深而宽的吸收轮廓,在靠近太阳边缘的安静区观测时,显示出明显的线性散射偏振信号。这样的信号显示出特征性的三峰结构,在线芯和扩展的翼瓣中具有尖锐的峰。线芯峰通过Hanle效应对磁场的存在敏感,然而已知Hanle效应不在线翼中操作。最近的理论研究表明,与以前认为的相反,机翼线偏振信号通过磁光效应(MO)也对磁场敏感。我们寻找这个最近发现的物理机制中的散射极化翼的钙I 4227线的观测指标。我们进行了一系列的光谱偏振观测这条线使用苏黎世成像偏光仪(ZIMPOL)相机在格雷戈里Coudé望远镜IRSOL(瑞士)和在GREGOR望远镜在特内里费岛(西班牙)。总的线偏振度和线偏振角的空间变化在所观察的线的翼中是明显可感知的。我们提供了一个详细的讨论,我们的观测结果表明,检测到的变化总是发生在纵向磁场存在的区域,从而支持理论预测,它们产生的MO效应。
英文摘要:
Several strong resonance lines, such as H I Ly-$α$, Mg II k, Ca II K, Ca I 4227 Å\, which are characterized by deep and broad absorption profiles in the solar intensity spectrum, show conspicuous linear scattering polarization signals when observed in quiet regions close to the solar limb. Such signals show a characteristic triplet-peak structure, with a sharp peak in the line core and extended wing lobes. The line core peak is sensitive to the presence of magnetic fields through the Hanle effect, which however is known not to operate in the line wings. Recent theoretical studies indicate that, contrary to what was previously believed, the wing linear polarization signals are also sensitive to the magnetic field through magneto-optical effects (MO). We search for observational indications of this recently discovered physical mechanism in the scattering polarization wings of the Ca I 4227 Å line. We performed a series of spectropolarimetric observations of this line using the Zurich IMaging POLarimeter (ZIMPOL) camera at the Gregory-Coudé telescope of IRSOL (Switzerland) and at the GREGOR telescope in Tenerife (Spain). Spatial variations of the total linear polarization degree and of the linear polarization angle are clearly appreciable in the wings of the observed line. We provide a detailed discussion of our observational results, showing that the detected variations always take place in regions where longitudinal magnetic fields are present, thus supporting the theoretical prediction that they are produced by MO effects.
The magnetic sensitivity of the Mg ii k line to the joint action of Hanle, Zeeman and magneto-optical effects
我们强调的主要结果的辐射转移调查的磁灵敏度的太阳Mg ii k共振线在2795.5埃,占汉勒和塞曼效应以及部分频率再分布(PRD)现象的共同作用。我们确认,在线中心,散射过程产生的线性极化信号是可测量的,并且它们是敏感的,通过汉勒效应,磁场的强度在5和50 G之间,大约。我们还表明,塞曼效应产生显着的圆偏振信号,特别是对于纵向磁场强于50 G,这可以用来估计通过熟悉的magnetographer公式的太阳色球的磁化。最新颖的结果是,磁光效应在线的翼中产生Q/I散射偏振图案的减小和U/I信号的出现(即,线偏振平面的旋转)。Q/I和U/I翼信号对弱(约5 G)和强磁场的敏感性扩大了Mg ii k线探测太阳安静和活动区域色球层的科学兴趣
The polarization angle in the wings of Ca i 4227: A new observable for diagnosing unresolved photospheric magnetic fields
当在靠近太阳边缘的安静区域观察时,许多强共振线显示出明显的线性偏振信号,由散射过程产生,具有扩展的翼瓣。最近的研究表明,与以前认为的相反,翼瓣通过磁光(MO)效应对相对弱的纵向磁场的存在敏感。我们从理论上研究了钙I 4227线的散射极化翼的MO效应的敏感性,我们探索其诊断推断光球磁场的纵向分量的信息的潜力。我们计算的强度和偏振轮廓的Ca I 4227线的数值求解问题的偏振辐射的产生和传输下的非局部热力学平衡条件下的太阳大气的一维半经验模型,考虑到联合行动的Hanle,塞曼,和MO效应。我们认为体积填充磁场以及磁场占据一小部分的分辨率元素。与塞曼效应产生的圆偏振信号相比,我们发现Ca I 4227的散射偏振翼中的线偏振角通过MO效应不仅对光球磁场的通量,而且对磁场所占的分辨率元素的分数具有明显的敏感性。我们确定的强共振线的翅膀作为一个有价值的观察诊断未解决的磁场的线性偏振角。与对所观测的大气区域的磁通量和其他特性的信息进行编码的可观测量结合使用,它可以提供对磁场的填充因子的约束。
Evidence for the Operation of the Hanle and Magneto-Optical Effects in the Scattering Polarization Signals Observed by CLASP2 Across the Mg II h and k Lines
The transfer of polarized radiation in resonance lines with partial frequency redistribution, J-state interference, and arbitrary magnetic fields. A radiative transfer code and useful approximations
我们提出的理论框架和数值方法,我们已经实现了解决的问题的产生和转移的偏振辐射的谱线的局部化学平衡,同时占散射偏振,部分频率重新分布,J-状态的干扰,和超精细结构。由此产生的辐射转移代码允许模拟任意强度和方向的磁场通过汉勒,不完整的Paschen-Back和磁光效应的影响。我们还评估了一系列的近似建模的散射偏振的强共振线的翅膀,这将是特别有用的三维辐射转移的数值密集的情况下的适用性。我们研究的适用性所考虑的近似使用我们的辐射转移代码模拟斯托克斯配置文件的Mg II H & K线和H I莱曼α线在磁化的太阳大气的一维模型。忽略多普勒再分布的散射过程中,未受扰动的弹性碰撞产生的误差可以忽略不计的散射偏振翼的Mg II共振线和一个轻微的莱曼α翼,虽然它是不适合的模型的核心,这些线。对于这两条线,由弹性碰撞扰动的散射过程给出了显着的贡献,只有发射率的强度分量。忽略碰撞和多普勒再分布,对于Mg II共振线的机翼来说是一个粗略但合适的近似,但对于Lyman α机翼来说是一个很差的近似。在所考虑的线的散射极化翼的磁灵敏度可以通过占磁场仅在η I和ρ V系数的斯托克斯矢量传输方程建模。
Gas dynamics in the inner few AU around the Herbig B[e] star MWC297: Indications of a disk wind from kinematic modeling and velocity-resolved interferometric imaging
1.5D investigation of the Hanle effect in the Ca I 4227 line using partial frequency redistribution. Comparison of synthetic Stokes profiles in Bifrost and MURaM-ChE rMHD models
Indian Institute of Astrophysics(印度天体物理研究所);Pondicherry University(本地治里大学);Max Planck Institute for Solar System Research(马普太阳系研究所);School of Space Research, Kyung Hee University(庆熙大学宇宙研究学院)
本研究通过Bifrost与MURaM-ChE rMHD模型,利用1.5维方法对比Ca I 4227线的Hanle效应,发现两者偏振轮廓差异源于热磁结构不同,MURaM-ChE线心磁化更弱。