Previous observations have not been able to exclude the possibility that high temperature active region loops are actually composed of many small scale threads that are in various stages of heating and cooling and only appear to be in equilibrium. With new observations from the EUV Imaging Spectrometer (EIS) and X-ray Telescope (XRT) on \textit{Hinode} we have the ability to investigate the properties of high temperature coronal plasma in extraordinary detail. We examine the emission in the core of an active region and find three independent lines of evidence for steady heating. We find that the emission observed in XRT is generally steady for hours, with a fluctuation level of approximately 15% in an individual pixel. Short-lived impulsive heating events are observed, but they appear to be unrelated to the steady emission that dominates the active region. Furthermore, we find no evidence for warm emission that is spatially correlated with the hot emission, as would be expected if the high temperature loops are the result of impulsive heating. Finally, we also find that intensities in the "moss", the footpoints of high temperature loops, are consistent with steady heating models provided that we account for the local expansion of the loop from the base of the transition region to the corona. In combination, these results provide strong evidence that the heating in the core of an active region is effectively steady, that is, the time between heating events is short relative to the relevant radiative and conductive cooling times.
Active Region Moss: Doppler Shifts from Hinode/EIS Observations
研究苔藓区的多普勒频移和多普勒频移与温度的关系,可以帮助我们了解活动区核心的加热过程。在本文中,我们使用了一个活跃的区域观测记录的极紫外成像光谱仪(EIS)在2007年12月12日出测量的多普勒频移的苔藓地区。我们通过定义Tripathi等人(2010年)推导的低密度截止值,将苔藓区域与其他活动区域区分开来。我们根据Young等人(2012)中描述的方法对EIS波长校准进行了非常仔细的分析。对于在log T = 5.85和log T = 6.25 K之间具有最大灵敏度的谱线,我们发现速度分布峰值在0 km/s附近,估计误差为4-5 km/s。分布的宽度随温度而减小。分布的平均值显示出随温度升高而增加的蓝移,并且分布也显示出朝向蓝移的不对称性。将这些结果与不同的日冕加热模型预测的观测值进行比较,我们发现这些结果与稳定和脉冲加热情景是一致的。然而,事实上,有大量的像素显示速度振幅超过5公里的不确定性的$^{-1}$是暗示脉冲加热。显然,需要进一步的观测约束来区分这两种加热情景。
Hinode and IRIS observations of the magnetohydrodynamic waves propagating from the photosphere to the chromosphere in a sunspot
磁流体动力学(MHD)波被认为是加热太阳色球层和日冕的能源。虽然在太阳大气中已经观测到了MHD波,但对大气中的能量传输和耗散缺乏定量的估计。我们同时进行了太阳黑子本影的Hinode和IRIS观测,以获得两个不同的大气层(光球层和低过渡区)的向上能量通量,并估计能量耗散。观测结果揭示了所观测到的物理量周期振荡的一些性质,如相位关系、时间行为和功率谱,从而得出结论:在光球层,慢模驻波占主导地位,其高频泄漏在色球层和下过渡区被观测为向上波。我们估计向上的能量通量在光球层水平为$2.0\times10^7$ erg cm $^{-2}$ s $^{-1}$,在低过渡区水平为$8.3\times10^4$ erg cm $^{-2}$ s $^{-1}$。能量通量之间的差异大于维持太阳黑子本影中色球层所需的能量,这表明观测到的波可以对太阳黑子本影中色球层的加热做出至关重要的贡献。相反,在较低的过渡区水平上得到的向上的能通量小于加热日冕所需的能通量,这意味着我们可能需要另一种加热机制。然而,我们应该注意到一种可能性,即由于不透明效应,色球层耗散的能量可能被高估。
Coronal active regions are studied using Hinode/EIS observations in the EUV line Fe XII λ195.12 by analyzing their line profiles from 2006 December to 2019 December. The period covers the last 2 yr of solar cycle 23 and solar cycle 24 fully. Active regions are the main source of magnetic field in the solar atmosphere, important in its heating and dynamics. Line profiles were obtained from various active regions spread across the Sun on a monthly basis from which we obtained the intensity, line width, Doppler velocity, and centroid and examined their variation during the solar cycle. The histog…
Spicules Intensity Oscillations in SOT/HINODE Observations
目标。利用HINODE/SOT的观测资料,研究了平静太阳、活动太阳和活动区太阳针状体强度随太阳边缘高度增加的相干振荡。直到过渡区的相干性的存在强化了通过能量传输和光球振荡进行日冕加热和太阳风的理论。方法.使用的时间序列从HINODE/SOT在Ca II H线,我们调查的振荡强度分布在不同高度以上的太阳翼。我们使用傅立叶和小波分析来测量在高度处的强度的主频峰,以及在两个特定高度处的振荡之间的相位差,以找到振荡的相干性的证据。最后,根据不同高度针状体的密度值,计算出针状体在能量平衡时所输送的能量和质量。为了扩展这项工作,我们还可以考虑在不同纬度的相干振荡,并建议研究可能从其他卫星的观测中获得的振荡。
A Sharp Look at Coronal Rain with Hinode/SOT and SST/CRISP
热带的智慧,当它是热的和密集的,我们可以期待雨可能也适用于太阳。事实上,观测和数值模拟已经表明,环足点的强烈加热,就像活跃区域的情况一样,使它们的日冕脱离热平衡,这可能导致一种被称为灾难性冷却的现象。在日冕中的局部压力损失之后,热等离子体在这些环中局部冷凝,并急剧冷却到色球温度。这些斑点在H-α和Ca II H中以分钟的时间尺度变得明亮,它们的动力学似乎更多地受到环中内部压力变化的影响,而不是重力。因此,它们成为磁场的追踪者,这导致了壮观的日冕雨,被观察到沿着日冕环落下。在这项工作中,我们报告的日冕雨的高分辨率观测与太阳光学望远镜(SOT)日出和CRISP在瑞典太阳望远镜(SST)。进行统计研究,其中属性,如速度和加速度的日冕雨的推导。我们展示了这种现象如何构成循环内部物理条件的诊断工具。此外,我们还分析了环状下落的日冕雨中的线状凝聚的横向振荡,并讨论了这种波的可能性质。这表明了日冕雨在日冕加热和日冕地震学领域中的重要作用。
We statistically estimate the conversion rate of the energy released during an active-region transient brightening to Doppler motion and thermal and non-thermal energies. We used two types of datasets for the energy estimation and detection of transient brightenings. One includes spectroscopic images of Fe xiv, Fe xv, and Fe xvi lines observed by the Hinode/EUV Imaging Spectrometer. The other includes images obtained from the 211 Åchannel of the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA). The observed active region was NOAA 11890 on November 09, 2013, and the day after that.…
Measurements of Outflow Velocities in On-Disk Plumes from EIS Hinode Observations
在过去的几十年里,羽流对太阳风的贡献一直是热门话题。Hinode上的极紫外成像光谱仪提供了一种独特的手段,通过对日冕发射线的直接多普勒频移测量来推断日冕高度的外流速度。这样的直接多普勒频移测量是不可能与以前的光谱仪。我们测量的外流速度在日冕高度在几个磁盘上的长持续时间的羽流,这是位于冕洞,并在整个观测期间显示出显着的蓝移。在一种情况下,烟羽的测量间隔4小时。推导出的出流速度是一致的,表明流动是准定常的。此外,我们提供了沿羽流的流出速度分布,发现在1.02 $R_{\odot}$时,经视线效应校正的速度可达到10 km s $^{-1}$,在1.03 $R_{\odot}$时可达到15 km s $^{-1}$,在1.05 $R_{\odot}$时可达到25 km s $^{-1}$。这种稳定加速的明显特征,加上羽流底部没有明显的蓝移,为羽流模型提供了一个重要的限制。在1.03 $R_{\odot}$的高度,EIS还推导出密度为1.3 $\times10^{8}$ cm $^{-3}$,导致质子通量约为4.2 $\times10^9$ cm $^{-2}$ s $^{-1}$换算为1 AU,这比假设径向膨胀的典型太阳风的质子输入高一个数量级。这表明,冕洞羽流可能是太阳风的一个重要来源。
A challenge in characterizing active region (AR) coronal heating is in separating transient (bursty) loop heating from the diffuse background (steady) heating. We present a method of quantifying coronal heating's bursty and steady components in ARs, applying it to FeXVIII (hot94) emission of an AR observed by SDO/AIA. The maximum, minimum, and average brightness values for each pixel, over a 24 hour period, yield a maximum-brightness map, a minimum-brightness map, and an average-brightness map of the AR. Running sets of such three maps come from repeating this process for each time step of run…
Evidence for coherent spicule oscillations by correcting Hinode/SOT Ca II H in the southeast limb of the Sun
由于光球波动而加热色球层、日冕和太阳风的波动理论由于观测到的波相干性的存在而得到加强。利用太阳光学望远镜(SOT)研究了日珥强度振荡的相干性。我们使用了2015年4月3日获得的Ca II H线的Hinode/SOT东南区域附近的时间序列,并将去卷积程序应用于骨针,以说明我们的恢复方法如何有效地作用于骨针等精细结构。此外,还利用小波变换分析了日缘以上不同高度的强度振荡。然后,在两个特定高度测量振荡之间的相位差,以寻找相干振荡的证据。小波变换的结果显示,在2,4,5.5,和6.5分钟在四个不同的高度的主周期峰。发现相干水平高于75%的主导频率在5.5和8.5 mHz左右。测量的平均相速度为155-360 km s-1。我们发现,平均相速度随高度增加。结果表明,相干波携带的能量通量进入日冕和日光层可能比以前的估计大几倍,以前的估计仅基于恒定的速度。我们提供了令人信服的证据向上传播的相干波的存在。
We present a magnetohydrodynamic (MHD) simulation of the coronal mass ejection (CME) on 13 December 2006 in the emerging delta-sunspot active region 10930, improving upon a previous simulation by Fan (2016) as follows. (1) Incorporate an ambient solar wind instead of using a static potential magnetic field extrapolation as the initial state. (2) In addition to imposing the emergence of a twisted flux rope, also impose at the lower boundary a random electric field that represents the effect of turbulent convection, which drives field-line braiding and produces resistive and viscous heating in t…
I report on observations of a set of magnetic loops above a region with late-phase flux emergence taken by IRIS, Hinode and SDO. The loop system consists of many transition region loop threads with size of 5--12\arcsec\ in length and $\sim0.5$\arcsec in width and coronal loops with similar length and $\sim2$\arcsec width. Although the loop system consists of threads with different temperatures, most individual loop thread have temperature in a narrow range. In the middle of the loop system, it shows clear systematic blue-shifts of about 10\,\kms\ in the transition region that is consistent wit…
Evidence of widespread hot plasma in a non-flaring coronal active region from Hinode/XRT
纳米耀斑,在空间上无法分辨的磁链中的短而强的热脉冲,现在被认为是解决日冕加热问题的主要候选者。然而,频繁出现的纳米耀斑要求耀斑热等离子体始终存在于日冕中。到目前为止,它的探测被证明是难以捉摸的,部分原因是预测的强度非常微弱。在这里,我们报告的一个活跃的区域观察到的5个过滤器的日之出/XRT在2006年11月的分析。我们已经使用的过滤器比率的方法来获得软,硬比率的温度和排放量的地图。这些图是近似的,因为等离子体被假设为沿着每个视线是等温的。尽管如此,最难的可用比率揭示了约10 MK的血浆的明显存在。为了获得更详细的等离子体特性的信息,我们进行了蒙特卡罗模拟假设各种非等温发射测量分布沿视线。我们发现,所观察到的过滤器的比率意味着双峰分布组成的一个强冷(log T ~ 6.3-6.5)的组件和较弱(百分之几)和较热(6.6 < log T < 7.2)的组件。数据与沿所有视线的双峰分布一致,即,整个活跃区域。我们还发现,从过滤器的比率推断的等温温度敏感地依赖于冷组件的精确温度。该分量的轻微偏移可能导致热分量在硬比率测量中被遮蔽。因此,以硬比率和软比率制作的温度图往往是反相关的。我们的结论是,这一观察结果支持存在广泛的nanoflaring活动的活跃区域。
We analyze and model a C5.7 two-ribbon solar flare observed by SDO, Hinode and GOES on 2011 December 26. The flare is made of many loops formed and heated successively over one and half hours, and their footpoints are brightened in the UV 1600 A before enhanced soft X-ray and EUV missions are observed in flare loops. Assuming that anchored at each brightened UV pixel is a half flaring loop, we identify more than 6,700 half flaring loops, and infer the heating rate of each loop from the UV light curve at the foot-point. In each half loop, the heating rate consists of two phases, an intense impu…
Three-dimensional magnetic reconnection in unipolar regions. A case study of coronal bright points in the Sun
Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM(巴黎萨克雷大学、巴黎西岱大学、法国原子能和替代能源委员会、法国国家科学研究中心);Instituto de Astrofísica de Canarias(加那利群岛天体物理研究所);Universidad de La Laguna, Dept. Astrofísica(拉古纳大学,天体物理学系);European Space Agency (ESA), European Space Research and Technology Centre (ESTEC)(欧洲空间局(ESA),欧洲空间研究与技术中心(ESTEC))