Aims: Out of a novel observing technique, we publish for the first time, SoHO-SUMER observations of the true spectral line profile of hydrogen Lyman-alpha in quiescent prominences. With SoHO not being in Earth orbit, our high-quality data set is free from geocoronal absorption. We study the line profile and compare it with earlier observations of the higher Lyman lines and recent model predictions. Methods: We applied the reduced-aperture observing mode to two prominence targets and started a statistical analysis of the line profiles in both data sets. In particular, we investigated the shape of the profile, the radiance distribution and the line shape-to-radiance interrelation. We also compare Ly-a data to co-temporal 1206 Si III data. Results: We find that the average profile of Ly-a has a blue-peak dominance and is more reversed, if the line-of-sight is perpendicular to the field lines. The contrast of Ly-a prominence emission rasters is very low and the radiance distribution differs from the log-normal distribution of the disk. Features seen in the Si III line are not always co-spatial with Ly-a emission. Conclusions: Our empirical results support recent multi-thread models, which predict that asymmetries and depths of the self-reversal depend on the orientation of the prominence axis relative to the line-of-sight.
Quiescent prominence dynamics observed with the Hinode Solar Optical Telescope . II. Prominence Bubble Boundary Layer Characteristics and the Onset of a Coupled Kelvin-Helmholtz Rayleigh-Taylor Instability
To understand the formation of quiescent solar prominences, the origin of their magnetic field structures, i.e., magnetic flux ropes (MFRs), must be revealed. We use three-dimensional magnetofriction simulations in a spherical subdomain to investigate the role of typical supergranular motions in the long-term formation of a prominence magnetic field. Time-dependant horizontal supergranular motions with and without the effect of Coriolis force are simulated on the solar surface via Voronoi tessellation. The vortical motions by the Coriolis effect at boundaries of supergranules inject magnetic h…
The first ionization potential (FIP) bias is currently used to trace the propagation of solar features ejected by the wind and solar eruptions (coronal mass ejections). The FIP bias also helps us to understand the formation of prominences, as it is a tracer for the solar origin of prominence plasma. This work aims to provide elemental composition and FIP bias in quiescent solar prominences. This is key information to link these features to remnants of solar eruptions measured in-situ within the heliosphere and to constrain the coronal or photospheric origin of prominence plasma. We used the di…
Small-scale, cyclic, transverse motions of plasma threads are usually seen in solar prominences, which are often interpreted as magnetohydrodynamic (MHD) waves. Here, we observed small-scale decayless transverse oscillations in a quiescent prominence, and they appear to be omnipresent. The oscillatory periods of the emission intensity and a proxy for the line-of-sight Doppler shift are about half period of the displacement oscillations. This feature agrees well with the fast kink-mode waves in a flux tube. All the moving threads oscillate transversally spatially in phase and exhibit no signifi…
The solar radiation in the Lyman-alpha spectral line of hydrogen plays a significant role in the illumination of chromospheric and coronal structures, such as prominences, spicules, chromospheric fibrils, cores of coronal mass ejections, and solar wind. Moreover, it is important for the investigation of the heliosphere, Earth's ionosphere, and the atmospheres of planets, moons, and comets. We derive a reference quiet-Sun Lyman-alpha spectral profile that is representative of the Lyman-alpha radiation from the solar disk during a minimum of solar activity. This profile can serve as an incident …
Simultaneous transverse and longitudinal oscillations in a quiescent prominence triggered by a coronal jet
在本文中,我们报告了2015年6月29日在静止日珥中同时进行的横向和纵向振荡的多波长观测。在活动区12373发生了一次C2.4耀斑,它与一对短带和一个远带有关。在耀斑的脉冲阶段,一个日冕喷流喷出的主耀斑网站,并在西北方向传播的$\sim$ 224 km s $^{-1}$的视速度。飞机的一部分在远处的丝带附近停了下来。剩下的一部分继续前进,最后停在了日珥的东边。一旦喷流遇到日珥,它就会推动日珥周期性地振荡。日珥东部的横向振荡可分为两个阶段。在阶段I中,初始振幅、速度、周期和阻尼时标分别为$\sim$ 4.5 μ m、$\sim$ 20 km s $^{-1}$、$\sim$ 25 min和$\sim$ 7.5 hr。在第二阶段,初始振幅增加到$\sim$ 11.3 Mm,而初始速度减半到$\sim$ 10 km s $^{-1}$。该周期增加了$\sim$ 3.5倍。日珥西部也经历了横向振荡。初始振幅仅为$\sim$ 2 μ m,速度小于10 km/s $^{-1}$。周期($\sim$ 27分钟)略长于I相的EP。在日珥以东,少数水平线经历了纵向振荡。初始振幅、速度、周期和阻尼时标分别为$\sim$ 52 μ m、$\sim$ 50 km s $^{-1}$、$\sim$ 99分钟和2.5小时。据我们所知,这是第一个由日冕喷流引发的日珥横向和纵向同时振荡的报告。
In the present work we derive a Differential Emission Measure (DEM) dis- tribution from a region dominated by spicules. We use spectral data from the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on-board the Solar Heliospheric Observatory (SoHO) covering the entire SUMER wavelength range taken off-limb in the Northern polar coronal hole to construct this DEM distribution using the CHIANTI atomic database. This distribution is then used to study the thermal properties of the emission contributing to the 171 Å channel in the Atmospheric Imaging Assembly (AIA) on-board…
Comparing UV/EUV line parameters and magnetic field in a quiescent prominence with tornadoes
上下文理解等离子体和磁场之间的密切关系对于描述和解释观测到的太阳磁场的复杂动力学是重要的。目的。我们确定,如果一个密切的关系,等离子体和磁场参数测量在一个良好的观测日珥与高空间分辨率可以找到。我们选择了2014年7月15日从太空(IRIS,Hinode,SDO)和地面(THEMIS)观察到的日珥。我们使用2D互相关技术对数据集进行稳健的共对准。我们推导出的磁场参数从分光偏振测量的He I D3线THEMIS。比较了IRIS观测到的Mg II h和k线的线比和视速度与磁场强度、倾角和方位角的关系。使用Hinode/EIS Fe XII线比率计算电子密度,并与THEMIS和IRIS数据进行比较。结果我们发现镁II k/h的比率约为1.4无处不在,类似于以前发现的值在brachiences。我们还发现,磁场是最强的(约30 G),主要是在龙卷风般的日珥腿水平。k3多普勒频移被发现是+/- 10公里/秒之间的任何地方。电子密度在1.5e6 K的温度下被发现是约1 e9/cm 3。磁场参数之间没有显着的相关性,和任何其他等离子体参数从EUV光谱推断,这可以解释在本研究中使用的线的温度的巨大差异。结论.这是第一次在日珥中以高空间分辨率对等离子体和磁场参数进行详细的统计研究。我们的研究结果提供了重要的约束未来模型的等离子体和磁场在这些结构。
A first look into the magnetic field configuration of prominence threads using spectropolarimetric data
我们显示了一个正在进行的调查,旨在确定配置的磁场向量的线程的一个静止的树篱日珥使用高空间分辨率的分光偏振观测在He I 1083.0 nm多重。数据包括一个静态的树篱日珥显示垂直线程的二维地图。这些观测是用特内里费岛红外线偏振计获得的,该偏振计安装在位于西班牙天文台的德国真空塔望远镜上。He I 1083.0 nm斯托克斯信号解释与反转码,它考虑到关键的物理过程,产生和/或修改圆和线性偏振信号在He I 1083.0 nm三重态:塞曼效应,各向异性辐射泵浦,和汉勒效应。我们目前的反演,即沿日珥和日珥线程的磁场矢量的强度和方向的初步结果。
Spectral Characteristics of the He I D3 Line in a Quiescent Prominence Observed by THEMIS
我们分析了一个静态日珥的观测望远镜Heliographique pour l 'Etude du Magnetisme et des Instabilites Solaires(THEMIS)在He I 5876 A(He I D3)多重峰,旨在测量He I D3轮廓的光谱特性,并为他们找到一个适当的拟合模型。用双高斯近似拟合系统测量了He I D3 Stokes I剖面的组分特性。该模型产生He I D3组分峰强度比为$5.5\pm0.4$,其不同于光学薄极限中预期的值8。大多数测得的多普勒速度位于$\pm5$ km/s区间内,在峰值0.4 km/s附近的标准偏差为$\pm1.7$ km/s。半峰全宽的宽分布对于He I D3蓝色分量在0.25 A和0.30 A处具有两个最大值,对于红色分量在0.22 A和0.31 A处具有两个最大值。组分的宽度比为$1.04\pm0.18$。我们表明,双高斯模型系统地低估了蓝翼强度。为了解决这个问题,我们调用了一个双温度多高斯模型,由两个双高斯,它提供了一个更好的表示,是免费的机翼强度赤字的He I D3。该模型认为目标日珥的冷、热分量的温度分别为11.5 kK和91 kK。典型的He ID 3分布的冷分量和热分量具有6.6和8的分量峰强度比,这意味着冷分量的突出几何宽度为17 μ m,光学厚度为0.3,而热分量的光学厚度可以忽略不计。这些突出…
Prominence plumes are evacuated upflows that emerge from bubbles below prominences, whose formation mechanism is still unclear. Here we present a detailed study of plumes in a quiescent prominence using the high-resolution H-alpha filtergrams at the line center as well as line wing at +/-0.4 angstrom from the New Vacuum Solar Telescope. Enhancements of brightening, blue shifts, and turbulence at the fronts of plumes are found during their formation. Some large plumes split at their heads and finger-shaped structures are formed between them. Blue-shifted flows along the bubble-prominence interf…
Propagating Waves Transverse to the Magnetic Field in a Solar Prominence
我们报告了一组不寻常的观测波在一个大的日珥柱,其中包括脉冲传播垂直于日珥磁场。2012年10月10日,我们用太阳动力学天文台(SDO)的大气成像组件(AIA)在EUV中观察到一个巨大的静止日珥,而只有一部分,即柱,这是日珥的一个脚或倒钩,用日出太阳光学望远镜(SOT)(Ca II和Hα系),Sac峰(Hα、Hβ和Na-D线),Themis(“Télescope Héliographique pour l' Etude du Magnétisme et des Instabilités Solaires”)与MTR(MultiTi-Raies)分光偏振计(He D_3线)。THEMIS/MTR数据表明,柱中的磁场基本上是水平的,并且在光学域中的观测显示出大量水平对齐的特征,其尺度比柱整体小得多。这些数据是一致的冷日珥等离子体被困在水平场线的倾角模型。SOT和Sac Peak在4小时观测期间的数据显示,垂直振荡表现为波脉冲。这些脉冲,其中包括多普勒签名,垂直移动,垂直于磁场方向,沿着薄准垂直列在更广泛的支柱。脉冲的传播速度约为10 km/s,周期约为300 sec,波长约为2000 km。我们解释这些波的快速磁声波,并讨论可能的波驱动程序。
Doppler-shifted Signatures in the Chromospheric Line Profiles of II Pegasi
Yunnan Observatories, Chinese Academy of Sciences(中国科学院云南天文台);Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences(中国科学院天体结构与演化重点实验室);International Centre of Supernovae, Yunnan Key Laboratory(超新星国际中心,云南省重点实验室);School of Astronomy and Space Science, University of Chinese Academy of Sciences(中国科学院大学天文与空间科学学院)