We developed a new technique for registration of the far solar corona from ground-based observations at distances comparable to those obtained from space coronagraphs. It makes possible visualization of fine details of studied objects invisible by naked eye. Here we demonstrate that streamers of the electron corona sometimes punch the dust corona and that the shape of the dust corona may vary with time. We obtained several experimental evidences that the far coronal streamers (observed directly only from the space or stratosphere) emit only in discrete regions of the visible spectrum like resonance fluorescence of molecules and ions in comets. We found that interaction of the coronal streamers with the dust corona can produce molecules and radicals, which are known to cause the resonance fluorescence in comets.
We propose that coronal heating in EUV coronal plumes is weaker, not stronger, than in adjacent non-plume coronal magnetic funnels. This expectation stems from (i) the observation that an EUV plume is born as the magnetic flux at the foot of the plume's magnetic funnel becomes tightly packed together, and (ii) the observation that coronal heating in quiet regions increases in proportion to the coast-line length of the underlying magnetic network. We do not rule out the possibility that coronal heating in EUV plumes might be stronger, not weaker, but we point out how the opposite is plausible. …
Dynamic features, such as chromospheric jets, transition region network jets, coronal plumes and coronal jets, are abundant in the network regions of the solar polar coronal holes. We investigate the relationship between chromospheric jets and coronal activities (e.g., coronal plumes and jets).We analyze observations of a polar coronal hole including the filtergrams that were taken by the New Vacuum Solar Telescope (NVST) at the Hα-0.6 Åto study the Hα jets,and the Atmospheric Imaging Assembly (AIA) 171 Å images to follow the evolution of coronal activities. Hα jets are persistent in the netwo…
Coronal holes are well accepted to be source regions of the fast solar wind. As one of the common structures in coronal holes, coronal plumes might contribute to the origin of the nascent solar wind. To estimate the contribution of coronal plumes to the nascent solar wind, we make the first attempt to estimate their populations in solar polar coronal holes. By comparing the observations viewed from two different angles taken by the twin satellites of STEREO and the results of Monte Carlo simulations, we estimate about 16--27 plumes rooted in an area of $4\times10^4$ arcsec$^2$ of the polar cor…
The coronal magnetic field, despite its overwhelming importance to the physics and dynamics of the corona, has only rarely been measured. Here, the electron density maps derived from images acquired during the total solar eclipse of August 21st, 2017 are employed to demonstrate a new technique to measure the coronal magnetic fields. The strength of the coronal magnetic fields is derived with a semiempirical formula relating the plasma magnetic energy density to the gravitational potential energy. The resulting values are compared with those provided by more advanced coronal field reconstructio…
Using EUV images and line-of-sight magnetograms from Solar Dynamics Observatory, we examine eight emerging bipolar magnetic regions (BMRs) in central-disk coronal holes for whether the emerging magnetic arch made any noticeable coronal jets directly, via reconnection with ambient open field as modeled by Yokoyama and Shibata (1995). During emergence, each BMR produced no obvious EUV coronal jet of normal brightness, but each produced one or more faint EUV coronal jets that are discernible in AIA 193 Å images. The spires of these jets are much fainter and usually narrower than for typical EUV j…
A differential emission measure (DEM) method is used to evaluate the relationship of the electron density and temperature before and after a coronal rain event during an active sun over the period from 20:10 UT on October 6 to 02:10 on October 7, 2011. Observational data were obtained from SDO/AIA for six different extreme ultraviolet (EUV) spectral lines. 240 different coronal loops were analyzed during this time interval, and the average electron density and temperature were obtained using 171 Å (Fe IX) and 193 Å (Fe XII) filters. The relationship between the density and temperature made it …
Time-evolving coronal modelling of the solar maximum around the solar storms in May 2024 by COCONUT
KU Leuven（荷语鲁汶大学）；University of Maria Curie-Skłodowska（玛丽亚·居里-斯可夫多夫斯卡大学）；Von Karman Institute For Fluid Dynamics（冯·卡门流体力学研究所）；University of Oslo（奥斯陆大学）
Solar coronal loops are commonly subject to oscillations. Observations of coronal oscillations are used to infer physical properties of the coronal plasma using coronal seismology. Excitation and evolution of oscillations in coronal loops is typically studied using highly idealised models of magnetic flux-tubes. In order to improve our understanding of coronal oscillations, it is necessary to consider the effect of realistic magnetic field topology and evolution. We study excitation and evolution of coronal oscillations in three-dimensional self-consistent simulations of solar atmosphere spann…
The hot solar corona exists because of the balance between radiative and conductive cooling and some counteracting heating mechanism which remains one of the major puzzles in solar physics. The coronal thermal equilibrium is perturbed by magnetoacoustic waves which are abundantly present in the corona, causing a misbalance between the heating and cooling rates. Due to this misbalance, the wave experiences a back-reaction, either losing or gaining energy from the energy supply that heats the plasma, at the time scales comparable to the wave period. In particular, the plasma can be subject to wa…
Coronal Bright Points (CBPs) are ubiquitous structures in the solar atmosphere composed of hot small-scale loops observed in EUV or X-Rays in the quiet Sun and coronal holes. They are key elements to understand the heating of the corona; nonetheless, basic questions regarding their heating mechanisms, the chromosphere underneath, or the effects of flux emergence in these structures remain open. We have used the Bifrost code to carry out a 2D experiment in which a coronal-hole magnetic nullpoint configuration evolves perturbed by realistic granulation. To compare with observations, synthetic SD…
Observing the fine structure of loops through high resolution spectroscopic observations of coronal rain with the CRISP instrument at the Swedish Solar Telescope
Magnetic Flux Cancelation as the Trigger of Solar Coronal-Hole Coronal Jets
我们详细调查的磁原因的微灯丝喷发，驱动日冕洞射流。我们研究了13个随机的盘上冕洞喷流喷发，使用高分辨率的X射线图像从Hinode/XRT，EUV图像从SDO/AIA，和磁图从SDO/HMI。对于所有13个事件，我们跟踪的喷气基地区域的演变，并发现一个minifilament的冷（过渡区温度）等离子体是目前每个喷喷发之前。HMI磁图显示微丝沿着多数极性和少数极性磁通量贴片之间的磁中性线存在。这些斑块相互会聚和抵消，所有13个喷流的平均抵消率约为0.6 X 1018 Mx hr^{-1}。中性线上持续的通量抵消最终使微丝场不稳定，微丝场向外爆发并产生喷流尖顶。因此，我们发现，所有13个冕洞喷流驱动的微暗条爆发是由中性线上的通量抵消触发的。这些结果与Panesar et al 2016 b最近对平静区喷流的发现一致，其中底层中性线处的通量抵消触发了驱动每个喷流的微丝喷发。因此，通过对宁静太阳喷流和冕洞喷流研究，我们认为通量抵消是触发宁静区和冕洞喷流的主要候选者
Magnetism defines the complex and dynamic solar corona. Coronal mass ejections (CMEs) are thought to be caused by stresses, twists, and tangles in coronal magnetic fields that build up energy and ultimately erupt, hurling plasma into interplanetary space. Even the ever-present solar wind possesses a three-dimensional morphology shaped by the global coronal magnetic field, forming geoeffective corotating interaction regions. CME evolution and the structure of the solar wind depend intimately on the coronal magnetic field, so comprehensive observations of the global magnetothermal atmosphere are…
The Dependence of the Peak Velocity of High-Speed Solar Wind Streams as Measured in the Ecliptic by ACE and the STEREO satellites on the Area and Co-Latitude of their Solar Source Coronal Holes
Diagnostics of Coronal Magnetic Fields Through the Hanle Effect in UV and IR Lines
太阳高层大气，特别是日冕中的等离子体热力学主要受磁场的控制，磁场控制着能量的流动和耗散。相对缺乏对日冕矢量磁场的了解是日冕物理学进展的一个主要障碍。这使得日冕磁场测量方法的发展成为太阳物理学中的一个高度优先事项。在紫外和红外谱线中的汉勒效应是一个很大程度上未开发的诊断。我们使用磁流体动力学（MHD）模拟研究的信号的幅度预期典型的日冕磁场选定的谱线在紫外线和红外线波长范围内，即H I Ly- $α$和He I 10830线。我们表明，选定的线是有用的可靠的诊断冠状磁场。结果表明，组合对Hanle效应敏感性不同的谱线的偏振测量，可能是从未来观测中推断日冕磁性质的最合适的方法。
We use full-disk, SOHO/EIT 195 $Å$ calibrated images to measure latitudinal and day to day variations of area and average photon fluxes of the near equatorial coronal holes. In addition, energy emitted by the coronal holes with their temperature and strength of magnetic field structures are estimated. By analyzing data of 2001-2008, we find that variations of average area (A), photon flux (F), radiative energy (E) and temperature (T) of coronal holes are independent of latitude. Whereas inferred strength of magnetic field structure of the coronal holes is dependent on the latitudes and varies …
Coronal mass ejections (CMEs) are huge expulsions of magnetized matter from the Sun and stars, traversing space with speeds of millions of kilometers per hour. Solar CMEs can cause severe space weather disturbances and consumer power outages on Earth, whereas stellar CMEs may even pose a hazard to the habitability of exoplanets. While CMEs ejected by our Sun can be directly imaged by white-light coronagraphs, for stars this is not possible. So far, only a few candidates for stellar CME detections are reported. Here we demonstrate a different approach, based on sudden dimmings in the extreme-ul…
