A Filament—Associated Halo Coronal Mass Ejection

1 INTRODUCTIONCoronal majss ejections (CMEs) are often seen as spectacular eruptions of matter fromthe Sun which propagate outward through the heliosphere and often interact with the Earth'smagnetosphere (Hundhausen, 1997; Gosling, 1997; and references herein). It is well known thatthese interactions can have substalltial consequences on the geomagnetic environment of theEarth, sometimes resulting in damage to satellites (e.g., McAllister et al., 1996; Berdichevskyet al., 1998). CMEs…     

晕状日冕物质抛射

主要介绍晕状日冕物质抛射（halo CMEs)的产生机制，包括向量磁场演化是怎样触发halo CMEa的：halo CME与耀斑，暗条活动的相互关系怎样，是否有规律可循，暗条爆发，耀斑等活动现象是如何相互联系的，halo CME事件是由一个活动区域或一个活动事件驱动物，还是多个活动区或多个活动事件相互作用的结果，给出两个halo CME的日面起源的观测例证，提出相反极笥的磁场对消是CME日面源区磁场演化的主要特征。     

对地日冕物质抛射研究

日冕物质抛射，作为太阳大气中频繁发生的极为壮观的活动现象，越来越受到太阳物理学家的关注。其中一类特殊的抛射事件－－对地日冕物质抛射，通常与大的地磁暴、行星际激波和高能粒子事件相伴生，具有强烈的地球物理效应，是影响空间天气的主要因素之一。概括了对地日冕物质抛射的研究现状，重点介绍了与对土日冕物质抛射事件相联系的光球向量磁场演化的观测研究成果，并由典型事件探讨了暗条爆发、耀五等剧烈太阳活动和对地日冕物质抛射之间的密切关系，提出了尚待解决的主要问题和进一步的研究方向。     

磁场重联和日冕物质抛射

Basic processes of magnetic reconnection and observations of coronal mass ejection are introduced. A possible mechanism of CME caused by magnetic rcconnection in the current sheet of solar corona is suggested.     

The Coronal Mass Ejection Waiting-Time Distribution

The distribution of times t between coronal mass ejections (CMEs) in the Large Angle and Spectrometric Coronagraph (LASCO) CME catalog for the years 1996–2001 is examined. The distribution exhibits a power-law tail (t) with an index –2.36±0.11 for large waiting times (t>10 hours). The power-law index of the waiting-time distribution varies with the solar cycle: for the years 1996–1998 (a period of low activity), the power-law index is –1.86±0.14, and for the years 1999–2001 (a period of higher activity), the index is –2.98±0.20. The observed CME waiting-time distribution, and its variation with the cycle, may be understood in terms of CMEs occurring as a time-dependent Poisson process. The CME waiting-time distribution is compared with that for greater than C1 class solar flares in the Geostationary Operational Environmental Satellite (GOES) catalog for the same years. The flare and CME waiting-time distributions exhibit power-law tails with very similar indices and time variation.     

On the Coronal Mass Ejection onset and Coronal Dimming

A comprehensive case and statistical study of CME onsets has been conducted on the solar limb using the CDS, LASCO and EIT instruments aboard the SOHO spacecraft. This is the first dedicated campaign to establish firmly the EUV signatures of CME onsets and is based on a series of low-corona observing campaigns made in 2002. The event database consisted of 36 multiple emission line sequences observed with CDS and the study builds, in particular, on studies of EUV coronal dimming which have been associated with CME onsets. We witness a range of dimming events in EUV coronal emission line data. Shorter events, commonly of duration < 4 hours, we find are indirectly associated with CME onsets whereas longer-duration dimmings (> 4 hours) appear to be either due to coronal evolution or rotational effects. However, for some CME onsets, where the CDS pointing was appropriate, no dimming was observed. Dimming observed in EIT typically occurred immediately after the launch of a loop or prominence, and in 5 out of 9 events there is evidence of a matter buildup within the loop before launch. A total of 10 events occurred where CDS was used to directly observe the CME footprint, but no relationship between these events was found. The results suggest that the response of the corona to a CME launch differs between the low (1.0 R _⊙≤R≤1.2 R _⊙) and middle (1.2 R _⊙<R≤2.0 R _⊙) corona regions, hence implying a difference between dimming observations conducted with different instruments.     

一个引人注目的CME事件与共生现象的分析研究

根据1991年6月15日发生的微波、分米波、米波、十米波等波段内射电爆发以及质子事件、地磁暴等进行了分析研究,认为产生各种物理过程的有效机制和动因是日冕物质抛射而非太阳耀斑。     

Short-Period Fluctuations in Coronal Mass Ejection Activity during Solar Cycle 23

We have constructed a time series of the number of coronal mass ejections (CMEs) observed by SOHO/LASCO during solar cycle 23. Using spectral analysis techniques (the maximum entropy method and wavelet analysis) we found short-period (< one year) semiperiodic activity. Among others, we found interesting periodicities at 193, 36, 28, and 25 days. We discuss the implications of such short-period activity in terms of the emergence and escape of magnetic flux from the convection zone, through the low solar atmosphere (where these periodicities have been found for numerous activity parameters), toward interplanetary space. This analysis shows that CMEs remove the magnetic flux in a quasiperiodic process in a way similar to that of magnetic flux emergence and other solar eruptive activity.     

日冕物质抛射的观测性质

综述日冕物质抛射的观测和持性，简短的前言之后，给出ＣＭＥ的发现经过及统计特性，着重介绍ＣＭＥ与其他种类太阳活动的相关。然后介绍ＣＭＥ的一般特性，包括可能与ＣＭＥ相关的一些物理过程的观测特性。初步结论是：ＣＭＥ是一种演变中的磁结构现象。     

Flux Accretion and Coronal Mass Ejection Dynamics

Coronal mass ejections (CMEs) are the primary drivers of severe space weather disturbances in the heliosphere. Models of CME dynamics have been proposed that do not fully include the effects of magnetic reconnection on the forces driving the ejection. Both observations and numerical modeling, however, suggest that reconnection likely plays a major role in most, if not all, fast CMEs. Here, we theoretically investigate the accretion of magnetic flux onto a rising ejection by reconnection involving the ejection’s background field. This reconnection alters the magnetic structure of the ejection and its environment, thereby modifying the forces acting upon the ejection, generically increasing its upward acceleration. The modified forces, in turn, can more strongly drive the reconnection. This feedback process acts, effectively, as an instability, which we refer to as a reconnective instability. Our analysis implies that CME models that neglect the effects of reconnection cannot accurately describe observed CME dynamics. Our ultimate aim is to understand changes in CME acceleration in terms of observable properties of magnetic reconnection, such as the amount of reconnected flux. This flux can be estimated from observations of flare ribbons and photospheric magnetic fields.     

Possible Detection of a Flare-associated Coronal Mass Ejection on an M-dwarf

We here report a probable detection of a stellar coronal mass ejection(CME) in active M dwarf KIC 8093473 by performing an analysis on its time resolved X-ray spectra observed by the XMM-Newton satellite. Compared to the value at the quiescent state and the interstellar one, our spectral modeling returns a marginal(and probably evolving) excess of hydrogen column density in the flare state at a significance level of 1σ, which can be understood by an additional absorption due to a flare-associate...     

基于空时显著性的日冕物质抛射检测

日冕物质抛射(Coronal Mass Ejection, CME)是一种剧烈的太阳爆发现象, 它会对行星际空间造成严重扰动, 进而影响人类生产、生活. 基于CME的时空显著性, 将显著性检测方法引入到CME检测中, 利用结构化矩阵分解SOHO (Solar and Heliospheric Observatory)的大角度光谱日冕仪(Large Angle and Spectrometric Coronagraph Experiment, LASCO) C2的日冕图像对应的特征矩阵, 从中恢复出稀疏部分获得显著前景. 然后考虑CME运动时产生的时间显著性, 从而去除非CME结构(如冕流), 得到最终检测结果. 实验表明, 以人工目录协调数据分析中心(Coordinated Data Analysis Workshop, CDAW)检测结果为基准时, 所提方法不仅在检测CME数量上比计算机辅助跟踪软件包(Computer Aided CME Tracking Software package, CACTus)和太阳爆发事件检测系统(Solar Eruptive Event Detection System, SEEDS)有优势, 还在CME中心角度和张角宽度等特征物理参数测量上比CACTus和SEEDS更接近CDAW目录参考值.     

Quadrupolar Dimmings During a Partial Halo Coronal Mass Ejection Event

We present detailed observations of the formations of four distinct coronal dimmings during a flare of 17 September 2002, which was followed by an eruption of a huge coronal loop system, and then an over-and-out partial halo coronal mass ejection (CME), with the same direction as the loop system eruption but laterally far offset from the flare site. Among the four dimmings, two compact ones were symmetrically located in the opposite polarity regions immediately adjacent to the highly sheared magnetic polarity inversion line in the flare region, and hence were probably composed of bipolar double dimmings due to a flux-rope eruption and represented its evacuated footpoints. However, another nearby compact dimming and a remote diffuse one were formed in the opposite polarity footpoint regions of the eruptive loop system, and thus probably consisted of a pair of dimmings magnetically linked by the erupting loop system and also indicated its evacuated footpoints. The loop system might have played a role in guiding the erupting flare field and producing the over-and-out CME, but its eruption might simply have been pushed out by the erupting flare field, because there was no reconnection signature between them. From comparison with a derived potential-field source-surface (PFSS) magnetic configuration, our observations consistently suggest that the dimmings were formed in pairs and originated from the eruptions of the two different magnetic systems. We thus define them as “quadrupolar dimmings.”     

Faraday Rotation Response to Coronal Mass Ejection Structure

We present the results from modeling the coronal mass ejection (CME) properties that have an effect on the Faraday rotation (FR) signatures that may be measured with an imaging radio antenna array such as the Murchison Widefield Array (MWA). These include the magnetic flux rope orientation, handedness, magnetic-field magnitude, velocity, radius, expansion rate, electron density, and the presence of a shock/sheath region. We find that simultaneous multiple radio source observations (FR imaging) can be used to uniquely determine the orientation of the magnetic field in a CME, increase the advance warning time on the geoeffectiveness of a CME by an order of magnitude from the warning time possible from in-situ observations at L ₁, and investigate the extent and structure of the shock/sheath region at the leading edge of fast CMEs. The magnetic field of the heliosphere is largely “invisible” with only a fraction of the interplanetary magnetic-field lines convecting past the Earth; remote sensing the heliospheric magnetic field through FR imaging from the MWA will advance solar physics investigations into CME evolution and dynamics.     

太阳日冕物质抛射特性的模糊分类研究

应用模糊集理论对日冕物质抛射（CME）特性进行分类研究，根据CME形态特性和特征因子之间的关系，重点阐明构造每个特性的隶属函数和确定权重因子的基本原理与方法，通过数据处理，对CME特性进行聚类分析，结果表明，模糊分类方法要优于传统的统计分析，对于CME特性按重要性分类，为空间环境的预报提供了一个具有实用价值的方法。     

Atmospheric Dynamics and Magnetic Activity Associated With A Coronal Mass Ejection

By using multi-wavelength observations, we explored the atmospheric dynamics and the surface magnetic activity in NOAA 9026, which were associated with the initiation of a halo coronal mass ejection (CME) on 6 June, 2000. In an interval of less than two hours, two X-class X-ray flares took place successively, each along with one eruption of a filament. However, only the second X-class flare which is characterized by a rather large-scale (larger than a general active region in area) EUV dimming was associated with the CME initiation. It seems that a flare with an extensive dimming is more likely to be CME-associated. We focused our study on the daily evolution of the vector magnetic field in this region from 4 to 9 June and have found the following results. (1) The gradual squeeze and cancellation of the opposite polarity magnetic fields are the main patterns of magnetic evolution. Moreover, there is a spatial coincidence between the sites of magnetic flux cancellation and the locations of the early filament activation and the flare brightenings. (2) The current system increased in the first two days and began to decrease at least ten hours before the CME initiation. It underwent dramatic disruption from 6 to 7 June. (3) The transverse component of the the vector magnetic field appeared helical in configuration. It changed from compact to loose and dissipated from a small to a large area. Here we suggest that although the first filament eruption and first flare were not in step with the CME initiation, they seem to be a part of the entire process. The observed evolution of the magnetic field implies a continuous transport of magnetic energy and complexity from the lower atmosphere to the corona. Moreover, the slow magnetic reconnection in the lower atmosphere, manifested as magnetic flux cancellation, and the helicity re-distribution, appear to play a key role in the energy build-up process of the flares and the initiation of the halo CME.     

日冕物质抛射研究进展

作为一种大尺度的太阳高能活动现象，日冕物质抛射（ＣＭＥ）的发现令人瞩目，其强烈的行星际和地球物理效应更引起了天文、空间和地球物理学家的共同关注。在本文中介绍了自ＣＭＥ发现以来的２２年中观测和研究所取得的进展，以及它给太阳物理学带来的影响，并分析了研究工作所面临的困难和障碍，展望了ＣＭＥ研究的前景。     

Dual-filament initiation of a Coronal Mass Ejection: Observations and Model

We propose a new model for the initiation of solar coronal mass ejections (CMEs) and CME-associated flares. The model is inferred from observations of a quiescent filament eruption in the north-western quadrant of the solar disk on 4 September 2000. The event was observed with the Siberian Solar Radio Telescope (5.7 GHz), the Nobeyama Radioheliograph (17 GHz) and SOHO/EIT and LASCO. Based on the observations, we suggest that the eruption could be caused by the interaction of two dextral filaments. According to our model, these two filaments merge together to form a dual-filament system tending to form a single long filament. This results in a slow upward motion of the dual-filament system. Its upward expansion is prevented by the attachment of the filaments to the photosphere by filament barbs as well as by overlying coronal arcades. The initial upward motion is caused by the backbone magnetic field (first driving factor) which connects the two merging filaments. Its magnetic flux increases slowly due to magnetic reconnection of the cross-interacting legs of these filaments. If a total length of the dual-filament system is large enough, then the filament barbs detach themselves from the solar surface due to magnetic reconnection between the barbs with oppositely directed magnetic fields. The detachment of the filament barbs completes the formation of the eruptive filaments themselves and determines the helicity sign of their magnetic fields. The appearance of a helical magnetic structure creates an additional upward-directed force (second driving factor). A combined action of these two factors causes acceleration of the dual-filament system. If the lifting force of the two factors is sufficient to substantially extend the overlying coronal magnetic arcade, then magnetic reconnection starts below the eruptive filament in accordance with the classical scheme, and the third driving factor comes into play.     

Multi-Wavelength Signatures of Magnetic Reconnection of a Flare-Associated Coronal Mass Ejection

The evolution of an X2.7 solar flare, that occurred in a complex β γ δ magnetic configuration region on 3 November 2003 is discussed by utilizing a multi-wavelength data set. The very first signature of pre-flare coronal activity is observed in radio wavelengths as a type III burst that occurred several minutes prior to the flare signature in Hα. This type III burst is followed by the appearance of a loop-top source in hard X-ray (HXR) images obtained from RHESSI. During the main phase of the event, Hα images observed from ARIES solar tower telescope, Nainital, reveal well-defined footpoint (FP) and loop-top (LT) sources. As the flare evolves, the LT source moves upward and the separation between the two FP sources increases. The co-alignment of Hα with HXR images shows spatial correlation between Hα and HXR footpoints, whereas the rising LT source in HXR is always located above the LT source seen in Hα. The evolution of LT and FP sources is consistent with the reconnection models of solar flares. The EUV images at 195 Å taken by SOHO/EIT reveal intense emission on the disk at the flaring region during the impulsive phase. Further, slow-drifting type IV bursts, observed at low coronal heights at two time intervals along the flare period, indicate rising plasmoids or loop systems. The intense type II radio burst at a time in between these type IV bursts, but at a relatively greater height, indicates the onset of CME and its associated coronal shock wave. The study supports the standard CSHKP model of flares, which is consistent with nearly all eruptive flare models. More importantly, the results also contain evidence for breakout reconnection before the flare phase.     

Transequatorial Filament Eruption and Its Link to a Coronal Mass Ejection

We revisit the Bastille Day flare/CME Event of 2000 July 14, and demonstrate that this flare/CME event is not related to only one single active region (AR). Activation and eruption of a huge transequatorial filament are seen to precede the simultaneous filament eruption and flare in the source active region, NOAA AR 9077, and the full halo-CME in the high corona. Evidence of reconfiguration of large-scale magnetic structures related to the event is illustrated by SOHO EIT and Yohkoh SXT observations, as well as, the reconstructed 3D magnetic lines of force based on the force-free assumption. We suggest that the AR filament in AR9077 was connected to the transequatorial filament. The large-scale magnetic composition related to the transequatorial filament and its sheared magnetic arcade appears to be an essential part of the CME parent magnetic structure. Estimations show that the filament-arcade system has enough magnetic helicity to account for the helicity carried by the related CMEs. In addition, rather global magnetic connectivity, covering almost all the visible range in longitude and a huge span in latitude on the Sun, is implied by the Nancay Radioheliograph (NRH) observations. The analysis of the Bastille Day event suggests that although the triggering of a global CME might take place in an AR, a much larger scale magnetic composition seems to be the source of the ejected magnetic flux, helicity and plasma. The Bastille Day event is the first described example in the literature, in which a transequatorial filament activity appears to play a key role in a global CME. Many tens of halo-CME are found to be associated with transequatorial filaments and their magnetic environment.