The Calm before the Storm: The Link between Quiescent Cavities and Coronal Mass Ejections

Gibson, S. E.; Foster, D.; Burkepile, J. T.; Toma, G. de; Stanger, A. L.

doi:10.1086/500446

Cited by 165 publications

(159 citation statements)

References 76 publications

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“…One the other hand, the bulged wavefront may reflect the enhanced Alfvén speed in the filament channel. Filament channels are known to be the disk counterpart of prominence cavities observed above the limb, which are characterized by higher magnetic field strength and lower plasma density than the surrounding corona (Leroy 1989;Gibson et al 2006). Liu et al (2012b) reported a fast EUV wave propagating through a cavity with an embedded filament at 50% faster speeds than outside, suggesting that the wave propagates at the local fast-mode velocity.…”

Section: Summary and Discussionmentioning

confidence: 99%

Observation of a Moreton Wave and Wave-Filament Interactions Associated With the Renowned X9 Flare on 1990 May 24

Liu

et al. 2013

ApJ

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Using Big Bear Solar Observatory film data recently digitized at NJIT, we investigate a Moreton wave associated with an X9 flare on 1990 May 24, as well as its interactions with four filaments F1-F4 located close to the flaring region. The interaction yields interesting insight into physical properties of both the wave and the filaments. The first clear Moreton wavefront appears at the flaring-region periphery at approximately the same time as the peak of a microwave burst and the first of two γ -ray peaks. The wavefront propagates at different speeds ranging from 1500-2600 km s −1 in different directions, reaching as far as 600 Mm away from the flaring site. Sequential chromospheric brightenings are observed ahead of the Moreton wavefront. A slower diffuse front at 300-600 km s −1 is observed to trail the fast Moreton wavefront about one minute after the onset. The Moreton wave decelerates to ∼550 km s −1 as it sweeps through F1. The wave passage results in F1's oscillation which is featured by ∼1 mHz signals with coherent Fourier phases over the filament, the activation of F3 and F4 followed by gradual recovery, but no disturbance in F2. Different height and magnetic environment together may account for the distinct responses of the filaments to the wave passage. The wavefront bulges at F4, whose spine is oriented perpendicular to the upcoming wavefront. The deformation of the wavefront is suggested to be due to both the forward inclination of the wavefront and the enhancement of the local Alfvén speed within the filament channel.

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Section: Summary and Discussionmentioning

confidence: 99%

Observation of a Moreton Wave and Wave-Filament Interactions Associated With the Renowned X9 Flare on 1990 May 24

Liu

et al. 2013

ApJ

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“…Aside from the spacecraft observations, the flux rope configuration also explains the white-light structure of CMEs (Chen 1996;Gibson & Low 1998. Gibson et al (2006) reported a more recent, comprehensive survey of white-light quiescent cavities (associated with a range of coronal loop morphologies) that suggested that the flux rope structure is formed prior to initiation of the CME.…”

Section: Flux Rope Modeling Of Cmesmentioning

confidence: 99%

VLA Measurements of Faraday Rotation through Coronal Mass Ejections

et al. 2017

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Coronal mass ejections (CMEs) are large-scale eruptions of plasma from the Sun that play an important role in space weather. Faraday rotation (FR) is the rotation of the plane of polarization that results when a linearly polarized signal passes through a magnetized plasma such as a CME and is proportional to the path integral through the plasma of the electron density and the line of sight component of the magnetic field.FR observations of a source near the Sun can provide information on the plasma structure of a CME shortly after launch; however, separating the contribution of the plasma density from the line of sight magnetic field is challenging.We report on simultaneous white-light and radio observations made of three CMEs in August 2012. We made sensitive Very Large Array (VLA) full-polarization observations using 1 − 2 GHz frequencies of a "constellation" of radio sources through the solar corona at heliocentric distances that ranged from 6 − 15R ⊙ . Of the nine sources observed, three were occulted by CMEs: two sources (0842+1835 and 0900+1832) were occulted by a single CME and one source (0843+1547) was occulted by two CMEs. In addition to our radioastronomical observations, which represent one of the first active hunts for CME Faraday rotation since Bird et al. (2007) and Jensen & Russell (2008), as well as previous CME FR observations by Bird et al. (1985).

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“…A flux rope structure, involving a set of twisted magnetic field lines around a central axis, is often used to interpret the three-part structure of a CME; for instance, the dark cavity and the bright core of the CME correspond to the whole flux rope and the magnetic dips of the flux rope, respectively (e.g., Low & Hundhausen 1995;Chen 1996;Gibson et al 2006;Riley et al 2008). Such helical flux rope configuration has been reconstructed using nonlinear force-free field models based on photospheric vector magnetogram data (e.g., Canou et al 2009;Cheng et al 2010;Guo et al 2010;Jing et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Differential Emission Measure Analysis of Multiple Structural Components of Coronal Mass Ejections in the Inner Corona

Cheng

Zhang

Saar

et al. 2012

ApJ

267

249

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In this paper, we study the temperature and density properties of multiple structural components of coronal mass ejections (CMEs) using differential emission measure (DEM) analysis. The DEM analysis is based on the sixpassband EUV observations of solar corona from the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory. The structural components studied include the hot channel in the core region (presumably the magnetic flux rope of the CME), the bright loop-like leading front (LF), and coronal dimming in the wake of the CME. We find that the presumed flux rope has the highest average temperature (>8 MK) and density (∼1.0 × 10 9 cm −3 ), resulting in an enhanced emission measure over a broad temperature range (3 T(MK) 20). On the other hand, the CME LF has a relatively cool temperature (∼2 MK) and a narrow temperature distribution similar to the pre-eruption coronal temperature (1 T(MK) 3). The density in the LF, however, is increased by 2%-32% compared with that of the pre-eruption corona, depending on the event and location. In coronal dimmings, the temperature is more broadly distributed (1 T(MK) 4), but the density decreases by ∼35%-∼40%. These observational results show that: (1) CME core regions are significantly heated, presumably through magnetic reconnection; (2) CME LFs are a consequence of compression of ambient plasma caused by the expansion of the CME core region; and (3) the dimmings are largely caused by the plasma rarefaction associated with the eruption.

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The Calm before the Storm: The Link between Quiescent Cavities and Coronal Mass Ejections

Cited by 165 publications

References 76 publications

Observation of a Moreton Wave and Wave-Filament Interactions Associated With the Renowned X9 Flare on 1990 May 24

Observation of a Moreton Wave and Wave-Filament Interactions Associated With the Renowned X9 Flare on 1990 May 24

VLA Measurements of Faraday Rotation through Coronal Mass Ejections

Differential Emission Measure Analysis of Multiple Structural Components of Coronal Mass Ejections in the Inner Corona

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