High resolution movies in 193 A from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamic Observatory SDO show apparent rotation in the leg of a prominence observed during a coordinated campaign. Such structures are commonly referred to as tornadoes. Time-distance intensity diagrams of the AIA data show the existence of oscillations suggesting that the structure is rotating.
The aim of this paper is to understand if the cool plasma at chromospheric temperatures inside the tornado is rotating around its central axis. The tornado was also observed in Halpha with a cadence of 30 seconds by the MSDP spectrograph, operating at the Solar Tower in Meudon. The MSDP provides sequences of simultaneous spectra in a 2D field of view from which a cube of Doppler velocity maps is retrieved.
The Halpha Doppler maps show a pattern with alternatively blueshifted and redshifted areas of 5 to 10 arcsec wide. Over time the blueshifted areas become redshifted and vice versa, with a quasi-periodicity of 40 to 60 minutes. Weaker amplitude oscillations with periods of 4 to 6 minutes are superimposed onto these large period oscillations.
The Doppler pattern observed in Halpha cannot be interpreted as rotation of the cool plasma inside the tornado. The H$α$ velocity observations give strong constraints on the possible interpretations of the AIA tornado
High-resolution observations from the $Interface~Region~Imaging~Spectrometer$ ($IRIS$) reveal the existence of a particular type of small solar jets, which arose singly or in clusters from a tornado-like prominence suspended in the corona. In this study, we perform a detailed statistical analysis of 43 selected mini-jets in the tornado event. Our results show that the mini-jets typically have: (1) a projected length of 1.0-6.0 Mm, (2) a width of 0.2-1.0 Mm, (3) a lifetime of 10-50 s, (4) a velocity of 100-350 km s$^{-1}$, and (5) an acceleration of 3-20 km s$^{-2}$. Based on spectral diagnosti…
Dynamics of a solar prominence tornado observed by SDO/AIA on 2012 November 7-8
我们使用太阳动力学天文台/大气成像组件在2012年11月7日至8日期间获得的171，304，193和211个谱线的时间序列来研究日珥龙卷风的详细动力学。龙卷风最早出现在07年11月08：00 UT，近地面，逐渐上升的平均速度$\sim$ 1.5 km s $^{-1}$，并持续超过30小时。时间-距离图显示两种模式的准周期性横向位移的龙卷风轴的周期为40和50分钟，在不同的阶段的龙卷风的发展。第一种模式发生在上升阶段，可以用扭曲龙卷风的向上运动来解释。第二种模式发生在演化的后期，此时龙卷风已经停止上升，可能是由龙卷风中的MHD扭结波或两个龙卷风线绕着一个共同的轴旋转引起的。后一种假说得到了以下事实的支持：龙卷风在准周期阶段有时表现出双重结构。211和193的谱线显示日珥/龙卷风上方有一个日冕空洞，它在世界时$\sim$ 13：00开始膨胀，并持续上升到太阳边缘上方。龙卷风最终变得不稳定，并于11月8日15：00（世界时）与相应的日珥一起爆发为日冕物质抛射（CME）。空洞和与龙卷风相关的日珥演化的最后阶段类似于磁爆发模型。另一方面，扭折不稳定性可能会破坏扭曲龙卷风的稳定性，因此日珥龙卷风可以作为日冕物质抛射的前兆。
We examine the dynamical behavior of white light polar plume structures in the inner corona that are observed from the ground during total solar eclipses, based on their EUV hot and cool emission line counterparts observed from space. EUV observations from SDO/AIA of a sequence of rapidly varying coronal hole structures are analyzed. Evidence of events showing acceleration in the 1.25 Mk line of Fe XII at 193 A is given. The structures along the plume show an outward velocity of about 140 kms-1 that can be interpreted as an upwards propagating wave in the 304 A and 171 A lines; higher speeds a…
Solar Magnetized Tornadoes: Rotational Motion in a Tornado-like Prominence
Su等人在2012年提出了一种新的解释，认为细丝的形成和喷发是由表面上的漩涡驱动的旋转磁性结构。当这些结构出现在边缘上方时，它们被认为是类似龙卷风的风暴。它们可能作为等离子体的来源和细丝的扭曲起着关键作用。然而，没有观测成功区分旋转运动的磁结构在龙卷风般的湍流从其他运动，如振荡和逆流等离子体流。在这里，我们报告的证据旋转运动在一个龙卷风般的突出。两条日冕线的光谱观测是由一个专门设计的Hinode/EIS观测程序获得的。这些数据揭示了在日珥腿中存在冷的和百万度的热等离子体，支持所谓的“日冕过渡区”。日珥两侧相反的速度和它们持续的时间演化，以及SDO/AIA暗结构中明显的周期性运动，表明冷、热等离子体都有一个旋转运动，速度为$\sim$ 5 km s $^{-1}$ .
We report on the tornado-like evolution of a quiescent prominence on 2014 November 1. The eastern section of the prominence first rose slowly transforming into an arch-shaped structure as high as ~150 Mm above the limb; the arch then writhed moderately in a left-handed sense, while the originally dark prominence material became in emission in the Fe IX 171~Å passband, and a braided structure appeared at the eastern edge of the warped arch. The unraveling of the braided structure was associated with a transient brightening in EUV and apparently contributed to the formation of a curtain-like str…
The triggering process for coronal mass ejections (CME) in the solar atmosphere is not fully understood. We use observations from different spacecraft at several wavelengths to detect an instability process for a prominence/filament with a subsequent eruption of CME. Time series of spectral lines at 304, 171, 193, and 211 Å have been obtained with the SDO spacecraft, and at 304, 171, 195, and 284 Å with the STEREO spacecraft. A prominence/filament system was observed during November 8-23, 2011, at different angles by SDO, STEREO_A, and STEREO_B. The observations show that a giant tornado began…
Since the Lalpha rocket observations of (Gabriel, Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three …
We present high-resolution observations of a magnetic reconnection event in the solar atmosphere taken with the New Vacuum Solar Telescope, AIA and HMI. The reconnection event occurred between the threads of a twisted arch filament system (AFS) and coronal loops. Our observations reveal that the relaxation of the twisted AFS drives some of its threads to encounter the coronal loops, providing inflows of the reconnection. The reconnection is evidenced by flared X-shape features in the AIA images, a current-sheet-like feature apparently connecting post-reconnection loops in the \halpha$+$1 Å ima…
Study of Two Successive Three-Ribbon Solar Flares on 2012 July 6
这封信报告了2012年7月6日在NOAA AR 11515中观察到的两个罕见的三带耀斑（M1.9和C9.2），我们用新太阳望远镜的0.1”分辨率的Halpha观测和Hinode的CaII H图像发现了这两个耀斑。耀斑网站的特点是一个有趣的“鱼骨状”的形态证明了这两个Halpha图像和非线性无力场（NLFFF）外推，其中两个半平行行的低洼，剪切环连接一个细长的，寄生的负场与寄生的正场。NLFFF模型还表明，这两排环的高度是不对称的，有相反的扭曲，并被大规模的磁力线，包括开放的领域。两次耀斑在半小时内相继发生，位于耀斑区的两端。每个耀斑的三个带状物平行于PIL，外部两个位于正磁场中，中心一个位于负磁场中。这两个耀斑都显示出明显朝向偏远地区的Halpha浪涌流，而C9.2耀斑也伴随着EUV喷流，可能沿着开放场线。有趣的是，C9.2耀斑的12-25 keV硬X射线源首先与中央带状物对齐，然后转移到集中在环的较高分支的顶部。这些结果进行了讨论有利于重联沿日冕零线产生的三个耀斑带和相关的喷射。
High-speed downflows have been observed in the solar transition region (TR) and lower corona for many decades. Despite their abundance, it has been hard to find signatures of such downflows in the solar chromosphere. In this work, we target an enhanced network region that shows ample occurrences of rapid spicular downflows in the \halpha\ spectral line that could potentially be linked to high-speed TR downflowing counterparts. We used the $k$-means algorithm to classify the spectral profiles of on-disk spicules in \halpha{} and \cak{} data observed from the Swedish 1-m Solar Telescope (SST) an…
Plasma diagnostics of an EIT wave observed by Hinode/EIS and SDO/AIA
我们提出了等离子体诊断的EIT波的观察与高节奏的Hinode/EIS坐盯光谱和SDO/AIA图像在HOP-180观测活动期间获得的2011年2月16日。在传播的EIT波前，我们观察到向下的等离子体流的EIS Fe XII，Fe XIII，和Fe XVI谱线（log T ~ 6.1-6.4）的视线（LOS）的速度高达20公里/秒。这些红移之后是蓝移，向上的速度高达-5 km/s，表明波前后面的等离子体弛豫。在波的演化过程中，向下的速度脉冲从几公里/秒变陡到20公里/秒，随后衰减，与线强度的相对变化相关。在EIT波阵面的等离子体密度的预期增加估计从观察到的强度增加位于我们的密度诊断从EIS XIII 202/203 AA线比的噪声水平。没有显着的LOS等离子体运动中观察到的He II线，这表明波脉冲是不够强，扰动底层色球。这与没有Halpha Moreton波与事件相关的结果一致。沿EIS狭缝传播的EIT波显示出~ -540 m/s ~ 2的强减速度和~ 590 km/s的起始速度。这些发现与日冕快模式MHD波的通过是一致的，它将等离子体向下推动并在日冕底部压缩。
