Downflows on the solar surface are suspected to play a major role in the dynamics of the convection zone. We investigate the existence of the long-lasting downflows whose effects influence the interior of the Sun and the outer layers.
We study the sets of Dopplergrams and magnetograms observed with SDO and Hinode spacecrafts and a MHD simulation. All of the aligned sequences, which were corrected from the satellite motions and tracked with the differential rotation, were used to detect the long-lasting downflows in the quiet-Sun at the disc centre. To learn about the structure of the flows below the solar surface, the time-distance local helioseismology was used.
The inspection of the 3D data cube (x, y, t) of the 24-hour Doppler sequence allowed us to detect 13 persistent downflows. Their lifetimes lie in the range between 3.5 and 20 hours with sizes between 2" and 3" and speeds between -0.25 and -0.72 km/s. These persistent downflows are always filled with the magnetic field with an amplitude of up to 600 G. The helioseismic inversion allows us to describe the persistent downflows and compare them to the other (non-persistent) downflows in the field of view. The persistent downflows seem to penetrate much deeper and, in the case of a well-formed vortex, the vorticity keeps its integrity to the depth of about 5 Mm. In the MHD simulation, only sub-arcsecond downflows are detected with no evidence of a vortex comparable in size to observations at the surface of the Sun.
The long temporal sequences from the space-borne allow us to show the existence of long-persistent downflows together with the magnetic field. They penetrate inside the Sun but are also connected with the anchoring of coronal loops in the photosphere, indicating a link between downflows and the coronal activity. A link suggests that EUV cyclones over the quiet Sun could be an effective way to heat the corona.
Observations of Supersonic Downflows in a Sunspot Light Bridge as Revealed by Hinode
最近从Hinode进行的高分辨率分光偏振观测发现了太阳黑子光桥中超音速下降流的存在（Louis等人，2009年）。这些下降流发生在局部补丁，接近该领域的方位角改变了一个大的值。这种明显的方位不连续性是沿着光桥西部边缘的一条薄脊看到的。其中一些（但不是全部）下流斑块与Ca II H滤光图中看到的色球亮度增强是同空间的。在0.3弧秒尺度下的磁场不均匀性的存在，可能有助于在较低的色球层中磁力线的重联，其特征可能是已经观察到的超音速下降流和亮度增强。
Helioseismic Signature of Chromospheric Downflows in Acoustic Travel-Time Measurements from Hinode
我们报告的一个签名的色球下降流在两个新兴的通量地区检测的时间距离日震学分析。我们使用Hinode/SOT获得的Ca II H线的色球强度振荡数据和Fe I 557.6nm线的光球多普勒数据进行分析。通过互相关的钙II振荡信号，我们已经检测到了一个旅行时间异常的plage地区，向外旅行时间比向内旅行时间短0.5-1分钟。然而，这样的异常是不存在的Fe I数据。这些结果可以解释为低色球层下行流的证据。下降速度估计低于10 km/s。这一结果表明，一个新的可能性研究色球流的时距分析。
Observations of Supersonic Downflows Near the Umbra-Penumbra Boundary of Sunspots as Revealed by Hinode
Hinode的高分辨率分光偏振观测揭示了3个太阳黑子的本影-半影边界处存在超音速下降流，这是Louis等人（2010年）最近报道的。观察到这些下行流与明亮的半影细丝共空间，并占据大于1.6弧秒$^2$的面积。它们位于中心侧的半影，与太阳黑子具有相同的极性，这表明它们与Evershed Flow无关。在本文中，我们描述了在NOAA AR 10923中观测到的超声速，并讨论了光球以及色球增亮，这是靠近下降区。我们的观测结果表明，这种现象是由动态和充满活力的物理过程中的内部半影影响上覆的色球层，从而提供了新的见解太阳黑子的数值模型。
Since May 1, 2010, we have been able to study (almost) continuously the vector magnetic field in the Sun, thanks to two space-based observatories: the Solar Dynamics Observatory (SDO) and Hinode. Both are equipped with instruments able to measure the Stokes parameters of Zeeman-induced polarization of photospheric line radiation. But the observation modes, the spectral lines, the spatial, spectral and temporal sampling, and even the inversion codes used to recover magnetic and thermodynamic information from the Stokes profiles are different. We compare the vector magnetic fields derived from o…
The Sun is the only star where the superficial turbulent convection can be observed at very high spatial resolution. The Solar Dynamics Observatory (SDO) has continuously observed the full Sun from space with multi-wavelength filters since July 2010. In particular, the Helioseismic and Magnetic Imager (HMI) instrument takes high-cadence frames (45 seconds) of continuum intensity in which solar granulation is visible. We aimed to follow the evolution of the solar granules over an activity cycle and look for changes in their spatial properties. We investigated the density of granules and their m…
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
We analyse observations of the X9.3 solar flare (SOL2017-09-06T11:53) observed by SDO/HMI and Hinode/SOT. Our aim is to learn about the nature of the HMI pseudocontinuum Ic used as a proxy for the white-light continuum. From model atmospheres retrieved by an inversion code applied to the Stokes profiles observed by the Hinode satellite we synthesise profiles of the FeI 617.3 nm line and compare them to HMI observations. Based on a pixel-by-pixel comparison we show that the value of Ic represents the continuum level well in quiet-Sun regions only. In magnetised regions it suffers from a simplis…
Exploding granules constitute the strongest horizontal flows on the quiet Sun and contribute to the structure of the surface horizontal velocity fields which build the large-scale organization of the discrete magnetic field. In this work we explore exploding granule expansion through the observations of the ground-based THEMIS telescope, IRIS, SDO, and the Hinode space-borne instruments, and finally with the magnetohydrodynamics simulation. We evaluate the detection and the expansion of exploding granules at several wavelengths and at various spatial and temporal resolutions. To analyze the di…
Photospheric magnetic vector maps from two different instruments are used to model the nonlinear force-free coronal magnetic field above an active region. We use vector maps inferred from polarization measurements of the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (HMI) and the Solar Optical Telescope Spectropolarimeter (SP) aboard Hinode. Besides basing our model calculations on HMI data, we use both, SP data of original resolution and scaled down to the resolution of HMI. This allows us to compare the model results based on data from different instruments and to investigate h…
University of Michigan（密歇根大学）；NorthWest Research Associates（西北研究协会）；Lockheed Martin Solar and Astrophysics Laboratory（洛克希德·马丁太阳与天体物理实验室）；Stanford University（斯坦福大学）；NASA GSFC（美国国家航空航天局戈达德太空飞行中心）
We investigate the cross-calibration of the Hinode/SOT-SP and SDO/HMI instrument meta-data, specifically the correspondence of the scaling and pointing information. Accurate calibration of these datasets gives the correspondence needed by inter-instrument studies and learning-based magnetogram systems, and is required for physically-meaningful photospheric magnetic field vectors. We approach the problem by robustly fitting geometric models on correspondences between images from each instrument's pipeline. This technique is common in computer vision, but several critical details are required wh…
University of Michigan（密歇根大学）；NASA GSFC（美国国家航空航天局戈达德太空飞行中心）；NorthWest Research Associates（西北研究协会）；Lockheed Martin Solar and Astrophysics Laboratory（洛克希德·马丁太阳与天体物理实验室）；Stanford University（斯坦福大学）
Both NASA's Solar Dynamics Observatory (SDO) and the JAXA/NASA Hinode mission include spectropolarimetric instruments designed to measure the photospheric magnetic field. SDO's Helioseismic and Magnetic Imager (HMI) emphasizes full-disk high-cadence and good spatial resolution data acquisition while Hinode's Solar Optical Telescope Spectro-Polarimeter (SOT-SP) focuses on high spatial resolution and spectral sampling at the cost of a limited field of view and slower temporal cadence. This work introduces a deep-learning system named SynthIA (Synthetic Inversion Approximation), that can enhance …
Statistics of convective collapse events in the photosphere and chromosphere observed with the Hinode SOT
目标。对流坍缩是一种理论上预测的过程，它会增强太阳大气层中现有的弱磁场，Nagata等人（2008年）首次使用日之出卫星的高分辨率太阳光学望远镜（SOT）在一次事件中直接观测到了这一过程。使用同一台太空望远镜，我们对对流坍缩事件进行了统计分析。方法.我们的数据集包括高分辨率时间序列的偏振光谱扫描的两个铁线形成在低光球层和过滤器的图像在Mg I B 2和Ca II H，谱线，形成在高光球层和低色球层，分别。因此，我们能够研究对流坍缩事件对高光球层和色球层的影响。用MERLIN Milne-Eddington反演程序得到了全Stokes剖面的物理参数。结果我们发现，在所有的情况下，该事件是伴随着一个连续的亮点，几乎总是由增亮的钙II H图像。镁多普勒图在镁多普勒图的视场内发生的事件中的约四分之三中表现出强的下行流。对于49个事件中的每一个，我们确定了持续时间，最大光球下降流，场强增加和大小。我们发现事件持续时间约为10分钟，磁性元素半径约为0.43弧秒和0.35弧秒，事件发生前后，分别和高达1.65千克的磁场强度。
Spectropolarimetry of Sunspot Penumbrae -- A Comprehensive Study of the Evershed Effect Using High Resolution Data from the Space-Borne Solar Observatory HINODE
Solar ultraviolet (UV) bursts are small-scale compact brightenings in transition region images. The spectral profiles of transition region lines in these bursts are significantly enhanced and broadened, often with chromospheric absorption lines such as Ni~{\sc{ii}} 1335.203 and 1393.330 Å superimposed. We investigate the properties of several UV bursts using a coordinated observation of the Interface Region Imaging Spectrograph (IRIS), Solar Dynamics Observatory (SDO), and \textit{Hinode} on 2015 February 7. We have identified 12 UV bursts, and 11 of them reveal small blueshifts of the Ni~{\sc…
日震和磁成像仪（HMI）刚刚开始产生数据，这些数据将有助于确定太阳内部变化的来源和机制。该仪器以相对较高的节奏测量整个太阳盘面上Fe I 6173 A线的多普勒频移和偏振，以研究太阳光球层全矢量磁场的振荡和演化。在数据经过适当校准后，将其提供给Milne-Eddington反演代码（VFISV，Borrero等人，2010年），其目的是推断太阳光球层中物理条件的某些方面，例如磁场的完整三维拓扑结构和太阳表面的视线速度。我们将简要描述反演代码的特点，它的优点和局限性-无论是在模式大气的背景下，数据的实际性质-和其他方面的性能，在这样一个显着的数据负载。此外，还将与来自日之出机载光谱偏振仪（SP）的近同时地图进行交叉比较。
Trees of fragmenting granules (TFG) and associated flows are suspected to playa major role in the formation of the network in the quiet Sun. We investigate the counterparts, in terms of dynamics, of surface structures detectable by high resolution observations in deeper layers up to 15 Mm, which are only available from numerical simulations. The first aim is to demonstrate that TFG can be evidenced either from surface intensitites, vertical (Vz), or Doppler (Vdop) velocities. The second is to show that horizontal flows, which are derived from intensities or Vz/Vdop flows, are in good agreement…
A Coronal Hole Jet Observed with Hinode and the Solar Dynamics Observatory
在2011年2月8日21：00 UT左右，在南极冕洞的边界观察到一个小的喷流。太阳动力学天文台（SDO）上的大气成像组件（AIA）的图像显示，一个膨胀的环从一个紧凑的双极亮点的一个脚点升起。SDO上的日震磁成像仪（HMI）的磁图显示，喷流是由亮点负极附近的寄生正极性特征抵消而触发的。喷流发射存在25分钟，并且从亮点延伸30 μ m。日之出号上的极紫外成像光谱仪测得的等离子体温度和密度分别为1.6 MK和0.9-1.7 x 10^8 cm^-3。视线速度高达250公里/秒，并发现随着高度的增加，这表明等离子体加速内的喷流。根据整个射流宽度的LOS速度的变化，发现了射流内扭转运动的证据。得到的角速度范围为9-12 x 10^-3 rad s^-1，与之前对喷流的测量结果一致。亮点的密度为7.6 x 10^8 cm^-3，亮点发射测量的峰值出现在1.3 MK，没有高于3 MK的等离子体。
We compare the properties of kG magnetic structures in the solar network and in active region plage at high spatial resolution. Our analysis used six SP scans of the solar disc centre aboard Hinode SOT and inverted the obtained spectra of the photospheric 6302 Åline pair using the 2D SPINOR code. Photospheric magnetic field concentrations in network and plage areas are on average 1.5 kG strong with inclinations of 10-20 degrees, and have <400 m/s internal and 2-3 km/s external downflows. At the disc centre, the continuum intensity of magnetic field concentrations in the network are on average …
Recently, there have been some reports of unusually strong photospheric magnetic fields (which can reach values of over 7 kG) inferred from Hinode SOT/SP sunspot observations within penumbral regions. These superstrong penumbral fields are even larger than the strongest umbral fields on record and appear to be associated with supersonic downflows. The finding of such fields has been controversial since they seem to show up only when spatially coupled inversions are performed. Here, we investigate and discuss the reliability of those findings by studying in detail observed spectra associated wi…
Instituto de Astrofísica de Canarias（加那利天体物理研究所）；Universidad de La Laguna（拉古纳大学）
The Helioseismic and Magnetic Imager (HMI) provides continuum images and magnetograms with a cadence better than one per minute. It has been continuously observing the Sun 24 hours a day for the past 7 years. The obvious trade-off between full disk observations and spatial resolution makes HMI not enough to analyze the smallest-scale events in the solar atmosphere. Our aim is to develop a new method to enhance HMI data, simultaneously deconvolving and super-resolving images and magnetograms. The resulting images will mimic observations with a diffraction-limited telescope twice the diameter of…
We analyse the spatial distribution of current helicity in solar active regions. A comparison of current helicity maps derived from three different instruments (Helioseismic and Magnetc Imager on board the Solar Dynamics Observatory, SDO/HMI, Spectro-Polarimeter on board the Hinode, and Solar Magnetic Field Telescope at the Huairou Solar Observing Station, China, HSOS/SMFT) is carried out. The comparison showed an excellent correlation between the maps derived from the spaceborne instruments and moderate correlation between the maps derived from SDO/HMI and HSOS/SMFT vector magnetograms. The r…
Chromospheric Jet and Growing "Loop" Observed by Hinode: New Evidence of Fan-Spine Magnetic Topology Resulting From Flux Emergence
我们目前的观测色球喷流和不断增长的“环”系统，显示了新的证据，扇脊拓扑结构导致磁通量出现。这一事件发生在2007年2月9日的赤道冕洞，由日野太阳光学望远镜在Ca II H线上以前所未有的细节观测到。喷流的前身是一束延伸到色球层上方的细物质线，似乎以约50 km/s（周期<200 s）的速度围绕束轴旋转。这些旋转或横向振荡以高达786 km/s的速度向上传播。这个星系团先是缓慢地向上摆动，然后迅速地向上摆动，转变发生在A4.9耀斑的开始。一个环在这两个阶段同时膨胀（速度：16-135 km/s）。在耀斑的峰值附近，环似乎破裂;同时向上喷出物和质量下降流比自由落体更快地出现在一个环腿。然后，物质束以鞭打的方式摆动回来，并发展成准直射流，其沿着推断出的开放场线取向，横向振荡以较慢的速率继续。一些物质沿着平滑的流线回落，不再显示振荡。在低海拔，流线分叉，大概在一个磁零点和绕过推断圆顶，描绘了一个倒Y几何形状。这些流线在空间上与晚期Ca II H环和X射线耀斑环密切匹配。这些观察结果与模型一致，即在开放场区域出现的磁通导致磁重联，形成喷流和扇脊拓扑结构。我们提出，物质束和准直射流分别代表准静态和喷发阶段的外脊，而生长环是三维扇面的二维投影。
High-resolution observations of the solar photosphere have recently revealed the presence of elongated filamentary bright structures inside sunspot umbrae. These features, which have been called umbral filaments (UFs), differ in morphology, evolution, and magnetic configuration from light bridges that are usually observed to intrude in sunspots. To study an UF observed in the leading sunspot of active region NOAA 12529, we have analyzed spectro-polarimetric observations taken in the photosphere with the spectropolarimeter (SP) aboard the Hinode satellite. High-resolution observations in the up…
Investigating prominence turbulence with Hinode SOT Dopplergrams
静止湍流有各种各样的流动，包括瑞利-泰勒不稳定性驱动的上升流和脉冲下降流，因此湍流运动也存在也就不足为奇了。由于磁流体湍流被认为具有平均水平引导场，因此研究它们所承载的任何湍流都可以揭示在广泛的天体物理系统中MHD湍流的性质。本文利用Hinode SOT观测资料构造的H $α$多普勒图，用结构函数分析方法研究了湍流日珥运动的性质。速度增量的pdf显示，当我们看到越来越小的空间间隔时，分布显示出与参考高斯分布的更大偏离，暗示了速度场的不稳定性。水平和垂直分离的偶数阶结构函数的分析表明，存在两个不同的区域，显示不同的幂律指数，在幂律中的突破约2000公里。我们假设这是一个结果的内部湍流激发的日珥的动态流动的系统在这个空间尺度。我们发现这两个区域的p阶结构函数的标度指数一般遵循p/2（小尺度）和p/4（大尺度）定律，这与弱MHD湍流和Kraichnan-Iroshnikov湍流的标度指数分别相同。然而，在比p/2标度更大的尺度上，p/4标度的存在与MHD湍流中预期的非线性增加不一致。从湍流能量耗散估算加热表明，这种湍流加热将是非常低效的，但是通过湍流驱动的重联的质量扩散是$10^{10}$ cm $^2$/s的量级。
