We analyze features that resemble type i spicules in two different 3D numerical simulations in which we include horizontal magnetic flux emergence in a computational domain spanning the upper layers of the convection zone to the lower corona. The two simulations differ mainly in the preexisting ambient magnetic field strength and in the properties of the inserted flux tube. We use the Oslo Staggered Code (OSC) to solve the full MHD equations with non-grey and non-LTE radiative transfer and thermal conduction along the magnetic field lines. We find a multitude of features that show a spatiotemporal evolution that is similar to that observed in type i spicules, which are characterized by parabolic height vs. time profiles, and are dominated by rapid upward motion at speeds of 10-30 km/s, followed by downward motion at similar velocities. We measured the parameters of the parabolic profile of the spicules and find similar correlations between the parameters as those found in observations. The values for height (or length) and duration of the spicules found in the simulations are more limited in range than those in the observations. The spicules found in the simulation with higher preexisting ambient field have shorter length and smaller velocities. From the simulations, it appears that these kinds of spicules can, in principle, be driven by a variety of mechanisms that include p-modes, collapsing granules, magnetic energy release in the photosphere and lower chromosphere and convective buffeting of flux concentrations.
Radiative MHD Studies of Solar Spicules: Driving Mechanisms and the Role of Background Magnetic Field
Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；University of Chinese Academy of Sciences（中国科学院大学）；Yunnan Key Laboratory of Solar Physics and Space Science（云南省太阳物理与空间科学重点实验室）；Solar Physics and Space Plasma Research Centre, School of Mathematical and Physical Sciences, University of Sheffield（谢菲尔德大学数学与物理科学学院太阳物理与空间等离子体研究中心）；Department of Astronomy, Eötvös Loránd University（厄特沃什·罗兰大学天文学系）；Gyula Bay Zoltán Solar Observatory (GSO), Hungarian Solar Physics Foundation (HSPF)（久洛·巴伊·佐尔坦太阳观测站（GSO），匈牙利太阳物理基金会（HSPF））
Using numerical simulations, we study the effects of magnetic resistivity and thermal conductivity in the dynamics and properties of solar jets with characteristics of Type II spicules and cool coronal jets. The dynamic evolution of the jets is governed by the resistive MHD equations with thermal conduction along the magnetic field lines on a 2.5D slice. The magnetic field configuration consists of two symmetric neighboring loops with opposite polarity, used to support reconnection and followed by the plasma jet formation. In total 10 simulations were carried out with different values of resis…
In addition to their jet-like dynamic behaviour, spicules usually exhibit strong transverse speeds, multi-stranded structure and heating from chromospheric to transition region temperatures. In this work we first analyse \textit{Hinode} \& \textit{IRIS} observations of spicules and find different behaviours in terms of their Doppler velocity evolution and collective motion of their sub-structure. Some have a Doppler shift sign change that is rather fixed along the spicule axis, and lack coherence in the oscillatory motion of strand-like structure, matching rotation models or long wavelength to…
On the Relationship between Solar Spicules and Propagating Coronal Disturbances: The Role of Shocks
Udaipur Solar Observatory, Physical Research Laboratory（乌代浦尔太阳观测台，物理研究实验室）；Indian Institute of Technology, Gandhinagar（印度理工学院，甘地纳加尔）；Indian Institute of Astrophysics（印度天体物理研究所）；Pondicherry University（本地治里大学）；School of Science, University of Newcastle（纽卡斯尔大学理学院）；Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematical and Physical Sciences, University of Sheffield（谢菲尔德大学数学与物理科学学院太阳物理与空间等离子体研究中心）；Department of Astronomy, Eötvös Loránd University（罗兰大学天文系）；Gyula Bay Zoltán Solar Observatory (GSO), Hungarian Solar Physics Foundation (HSPF)（久洛·拜·佐尔坦太阳观测台，匈牙利太阳物理基金会）
The role of type II spicules in the corona has been a much debated topic in recent years. This paper aims to shed light on the impact of type II spicules in the corona using novel 2.5D radiative MHD simulations including ion-neutral interaction effects with the Bifrost code. We find that the formation of simulated type II spicules, driven by the release of magnetic tension, impacts the corona in various manners. Associated with the formation of spicules, the corona exhibits 1) magneto-acoustic shocks and flows which supply mass to coronal loops, and 2) transversal magnetic waves and electric c…
It is known that hydrodynamic triangular jets are unstable to antisymmetric kink perturbations. The inclusion of magnetic field may lead to the stabilisation of the jets. Jets and complex magnetic fields are ubiquitous in the solar atmosphere, which suggests the possibility of the kink instability in certain cases. The aim of the paper is to study the kink instability of triangular jets sandwiched between magnetic tubes/slabs and its possible connection to observed properties of the jets in the solar atmosphere. A dispersion equation governing the kink perturbations is obtained through matchin…
We perform a 2.5 dimensional magnetohydrodynamic (MHD) simulation to understand a comprehensive view of the formation of spicule-like cool jets due to initial transverse velocity pulses akin to Alfvén pulses in the solar chromosphere. We invoke multiple velocity ($V_{z}$) pulses between 1.5 and 2.0 Mm in the solar atmosphere, which create the initial transverse velocity perturbations. These pulses transfer energy non-linearly to the field aligned perturbations due to the ponderomotive force. This physical process further creates the magnetoacoustic shocks followed by quasi-periodic plasma moti…
Jet phenomena with a bright loop in their footpoint, called anemone jets, have been observed in the solar corona and chromosphere. These jets are formed as a consequence of magnetic reconnection, and from the scale universality of magnetohydrodynamics (MHD), it can be expected that anemone jets exist even in the solar photosphere. However, it is not necessarily apparent that jets can be generated as a result of magnetic reconnection in the photosphere, where the magnetic energy is not dominant. Furthermore, MHD waves generated from the photospheric jets could contribute to chromospheric heatin…
We investigate high resolution spectroscopic and imaging observations from the CRisp Imaging SpectroPolarimeter (CRISP) instrument to study the dynamics of chromospheric spicule type events. It is widely accepted that chromospheric fine structures are waveguides for several types of magnetohydrodynamic (MHD) oscillations, which can transport energy from the lower to upper layers of the Sun. We provide a statistical study of 30 high frequency waves associated with spicule type events. These high frequency oscillations have two components of transverse motions: the plane of sky (POS) motion and …
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…
Observations, analysis and interpretation with non-LTE of chromospheric structures of the Sun
这篇论文是基于在真空塔望远镜（特内里费岛）进行的观测。从2004年到2006年，我们使用了红外分光偏振仪（TIP）和法布里-珀罗光谱仪（G-FPI）。我们应用了几种成像散斑重建技术，并对它们进行了比较。我们利用具有很高的空间、光谱和时间分辨率的Hα研究了太阳盘内部和边缘的色球动力学。关键词（详见全文摘要）：纤丝，浪涌，MHD波，斑点，盲解卷积，Fabry-Perot，迷你耀斑，云模型，Halpha中的针状体，在圆盘上继续的针状体）我们用He I 10830研究了远缘针状体光谱I随高度的变化。分析表明，作为到可见太阳临边的距离的函数的离临边发射分布的变化。研究了多重态的强度比（与光学厚度和日冕辐射有关），并与标准大气模型进行了比较。我们报告的观测性能，从高分辨率的H $α$谱线与G-FPI的过滤图。我们发现，骨针可以达到8毫米以上的肢体。我们表明，骨针外的肢体继续作为黑暗的原纤维内的光盘。
Two-dimensional Radiative Magnetohydrodynamic Simulations of Partial Ionization in the Chromosphere. II. Dynamics and Energetics of the Low Solar Atmosphere
Using simulated data-driven three-dimensional resistive MHD simulations of the solar atmosphere, we show that magnetic reconnection can be responsible of the formation of jets with characteristic of Type II spicules. For this, we numerically model the photosphere-corona region using the C7 equilibrium atmosphere model. The initial magnetic configuration is a 3D potential magnetic field, extrapolated up to the solar corona region from a dynamic realistic simulation of solar photospheric magnetoconvection model which is mimicking quiet-Sun. In this case we consider a uniform and constant value o…
Rapid blue- and red-shifted events (RBEs/RREs) may have an important role in mass-loading and heating the solar corona, but their nature and origin are still debatable. We aim to model these features to learn more about their properties, formation and origin. A realistic three-dimensional (3D) magneto-hydrodynamic (MHD) model of a solar plage region is created. Synthetic H$α$ spectra are generated and the spectral signatures of these features are identified. The magnetic field lines associated with these events are traced and the underlying dynamic is studied. The model reproduces well many pr…
The solar atmosphere is extremely dynamic, and many important phenomena develop on small scales that are unresolved in observations with the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO). For correct calibration and interpretation of the observations, it is very important to investigate the effects of small-scale structures and dynamics on the HMI observables, such as Doppler shift, continuum intensity, spectral line depth, and width. We use 3D radiative hydrodynamics simulations of the upper turbulent convective layer and the atmosphere of the Sun, …
Within the framework of resistive MHD, implementing the C7 equilibrium atmosphere model and a 3D potential magnetic field realistic configuration, we simulate the formation of a plasm jet with the morphology, upward velocity up to 130 km/s and timescale formation between 60 and 90 s after beginning of simulation, similar to those expected for Type II spicules. Initial results of this simulation were published in Paper (e.g., González-Avilés et al. 2018) and present paper is devoted to the analysis of transverse displacements and rotational type motion of the jet. Our results suggest that 3D ma…
Data-driven simulation is becoming an important approach for realistically characterizing the configuration and evolution of solar active regions, revealing the onset mechanism of solar eruption events and hopefully achieving the goal of accurate space weather forecast, which is beyond the scope of any existing theoretical modelling. Here we performed a full 3D MHD simulation using the data-driven approach and followed the whole evolution process from quasi-static phase to eruption successfully for solar active region NOAA 11429. The MHD system was driven at the bottom boundary by photospheric…
Modeling the Excitation, Propagation and Damping of Quasi-Periodic Fast Magnetosonic Waves in Realistic Coronal Active Region Magnetic Field Structures
Catholic University of America（美国天主教大学）；NASA Goddard Space Flight Center（NASA戈达德太空飞行中心）；Tel Aviv University（特拉维夫大学）；University of Hawaii at Mānoa（夏威夷大学马诺阿分校）；Lockheed Martin Solar and Astrophysics Laboratory（洛克希德·马丁太阳与天体物理实验室）
What Is the Source of Quiet Sun Transition Region Emission?
追溯到对盘上日冕的第一次观测，光球的磁网络和增强的转变温度等离子体发射之间存在着定性的联系。这些观测结果导致了一个通用模型的发展，该模型通过划分具有不同能量平衡的不同磁环几何形状的大气体积来描述发射结构。互联网络是否产生过渡温度辐射？有多少网络通量连接到日冕？安静的太阳辐射与低活动的类太阳恒星相比如何？在这项工作中，我们重新审视了安静太阳的规范模型，并利用IRIS和HMI的高分辨率观测数据来解决这些问题。我们使用超过900深曝光的硅IV 1393 A IRIS随着几乎同时HMI磁图量化之间的相关性过渡温度发射结构和磁场浓度通过一些新的统计。我们的观测结果与分析的Bifrost MHD模型和一个大规模的位场模型。我们的研究结果描绘了一幅安静的太阳的复杂肖像。我们测量的排放签名在遥远的互联网，不能归因于网络的贡献。我们发现，最暗淡的地区的发射是没有联系到当地的垂直磁场。利用MHD模拟，我们将冷的中高空冕环和高空冕环的辐射贡献进行了分类，并讨论了针状体的潜在辐射贡献。我们的结果为耦合太阳大气提供了新的约束，以便我们可以进一步了解动态热结构和磁结构如何在过渡区产生观察到的现象。
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…
We present a new MHD wave decomposition method that overcomes the limitations of existing wave identification methods. Our method allows to investigate the energy fluxes in different MHD modes at different locations of the solar atmosphere as waves generated by vortex flows travel through the solar atmosphere and pass near the magnetic null. We simulate wave dynamics through a coronal null configuration and apply a rotational wave driver at our bottom photospheric boundary. To identify the wave energy fluxes associated with different MHD wave modes, we employ a wave-decomposition method that i…
Quasi-Periodic Fast-Mode Wave Trains Associated with the 2015-Jun-22 M6.5 Flare in AR~12371: Observations and 3D MHD Modeling
Catholic University of America（美国天主教大学）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；Bay Area Environmental Research Institute（湾区环境研究所）；Lockheed Martin Solar and Astrophysics Laboratory（洛克希德·马丁太阳与天体物理实验室）；Institute for Astronomy, University of Hawai‘i at Mānoa（夏威夷大学马诺阿分校天文学研究所）
Context. On the sun, the magnetic field vector is measured routinely only in the photosphere. By using these photospheric measurements as boundary condition, we developed the magnetohydrostatic (MHS) extrapolation to model the solar atmosphere. The model makes assumption about the relative importance of magnetic and non-magnetic forces. While the solar corona is force-free, this is not the case in photosphere and chromosphere. Aim. The model has been tested with an exact equilibria in \cite{zw18}. Here we present a more challenging and realistic test of our model with radiative MHD simulation …
Recent observations at high spatial resolution have shown that magnetic flux cancellation occurs on the solar surface much more frequently than previously thought, and so this led Priest et al 2018 to propose magnetic reconnection driven by photospheric flux cancellation as a mechanism for chromospheric and coronal heating. In particular, they estimated analytically the amount of energy released as heat and the height of the energy release during flux cancellation. In the present work, we take the next step in the theory by setting up a two-dimensional resistive MHD simulation of two canceling…
