Material ejection

Webb, D. F.; Forbes, T. G.; Auraß, H.; Chen, J.; Martens, P. C. H.; Rompolt, B.; Rusin, V.; Martin, Sara

doi:10.1007/bf00712493

Cited by 52 publications

(22 citation statements)

References 45 publications

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“…Coronagraph images show that the physical structures of CMEs are primarily related to extended regions of closed magnetic fields in the quiet corona, and that the onset of CMES are triggered by instabilities in these fields (see reviews by Hundhausen, 1993;Webb et al, 1994). VLA observations at 91 cm have indicated that noise storm emission was associated with large-scale magnetic structures where a CME eventually occurred (Habbal et al, 1996), and the onset of two CMEs detected with the LASCO corongraphs has been associated with the enhancement of prexisting nonthermal radio noise storms (Aurass et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Very Large Array and SOHO Observations of Type I Noise Storms, Large-Scale Loops and Magnetic Restructuring in the Corona

Willson

2005

Sol Phys

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Very Large Array (VLA) observations at 91-cm wavelength are combined with data from the SOHO EIT, MDI and LASCO and used to study the evolving coronal magnetic environment in which Type I noise storms and large-scale coronal loops occur. On one day, we have shown the early evolution of a coronal mass ejection (CME) in projection in the disk by tracing its decimetric continuum emission. The passage of the CME and an associated EUV ejection event coincided with an increase in the 91-cm brightness temperature of an extended coronal loop located a significant distance away and with the displacement of the 91-cm source during the early stage of the CME. We suggest that the energy deposited into the corona by the CME may have caused a local increase in the thermal or nonthermal electron density or in the electron temperature in the middle corona resulting in a transient increase in the brightness of the 91-cm loop. On a second observing day, we have consolidated the known association between magnetic changes in the photosphere and low corona with noise storm enhancements in an overlying radio source well in advance of a flare event in the same region. We find anti-correlated changes in the brightness of a bipolar 91-cm Type I noise storm that appear to be associated with the cancellation and emergence of magnetic flux in the underlying photosphere. In this case, the evolving fields may have led to magnetic instabilities and reconnection in the corona and the acceleration of nonthermal particles that initiated and sustained the Type I noise storm.

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Section: Introductionmentioning

confidence: 99%

Very Large Array and SOHO Observations of Type I Noise Storms, Large-Scale Loops and Magnetic Restructuring in the Corona

Willson

2005

Sol Phys

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“…Coronal mass ejections (CMEs) are large-scale eruptive phenomena from the Sun. They can carry large amounts of plasma and magnetic field energy into the interplanetary space, which may have severe effects on space environment and human technological systems around the Earth (Gosling et al 1993;Webb et al 1994). A typical CME has a velocity of several hundred km s −1 , while the fastest one recorded is over 3000 km s −1 (Yashiro et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Formation and Separation of an Extreme-Ultraviolet Wave From the Expansion of a Coronal Mass Ejection

Cheng

Zhang

Olmedo

et al. 2011

ApJ

118

111

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We address the nature of EUV waves through direct observations of the formation of a diffuse wave driven by the expansion of a coronal mass ejection (CME) and its subsequent separation from the CME front. The wave and the CME on 2011 June 7 were well observed by Atmospheric Imaging Assembly onboard Solar Dynamic Observatory. Following the solar eruption onset, marked by the beginning of the rapid increasing of the CME velocity and the X-ray flux of accompanying flare, the CME exhibits a strong lateral expansion. During this impulsive expansion phase, the expansion speed of the CME bubble increases from 100 km s −1 to 450 km s −1 in only six minutes. An important finding is that a diffuse wave front starts to separate from the front of the expanding bubble shortly after the lateral expansion slows down. Also a type-II burst is formed near the time of the separation. After the separation, two distinct fronts propagate with different kinematic properties. The diffuse front travels across the entire solar disk; while the sharp front rises up, forming the CME ejecta with the diffuse front ahead of it. These observations suggest that the previously termed EUV wave is a composite phenomenon and driven by the CME expansion. While the -2 -CME expansion is accelerating, the wave front is cospatial with the CME front, thus the two fronts are indiscernible. Following the end of the acceleration phase, the wave moves away from the CME front with gradually an increasing distance between them.

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“…In large eruptions the magnetic flux of some 10 23 Wb is expelled into the interplanetary space at velocities of the order of 1000 km s −1 , carrying along 10 13 kg of coronal plasma (Gosling 1990;Webb et al 1994).…”

Section: Introductionmentioning

confidence: 99%

Kinematics of coronal mass ejections between 2 and 30 solar radii

Vršnak¹,

Ruždjak²,

Sudar³

et al. 2004

A&A

130

107

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Abstract. Kinematics of more than 5000 coronal mass ejections (CMEs) measured in the distance range 2-30 solar radii is investigated. A distinct anticorrelation between the acceleration, a, and the velocity, v, is found. In the linear form, it can be represented as a = −k 1 (v − v 0 ), where v 0 = 400 km s −1 , i.e., most of CMEs faster than 400 km s −1 decelerate, whereas slower ones generally accelerate. After grouping CMEs into the width and mean-distance bins, it was found that the slope k 1 depends on these two parameters: k 1 is smaller for CMEs of larger width and mean-distance. Furthermore, the obtained CME subsets show distinct quadratic-form correlations, of the form a = −k 2 (v − v 0 )|v − v 0 |. The value of k 2 decreases with increasing distance and width, whereas v 0 increases with the distance and is systematically larger than the slow solar wind speed by 100-200 km s −1 . The acceleration-velocity relationship is interpreted as a consequence of the aerodynamic drag. The excess of v 0 over the solar wind speed is explained assuming that in a certain fraction of events the propelling force is still acting in the considered distance range. In most events the inferred propelling force acceleration at 10 solar radii ranges between a L = 0 and 10 m s −2 , being on average smaller at larger distances. However, there are also events that show a L > 50 m s −2 , as well as events indicating a L < 0. Implications for the interplanetary motion of CMEs are discussed, emphasizing the prediction of the 1 a.u. arrival time.

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Material ejection

Cited by 52 publications

References 45 publications

Very Large Array and SOHO Observations of Type I Noise Storms, Large-Scale Loops and Magnetic Restructuring in the Corona

Very Large Array and SOHO Observations of Type I Noise Storms, Large-Scale Loops and Magnetic Restructuring in the Corona

Investigation of the Formation and Separation of an Extreme-Ultraviolet Wave From the Expansion of a Coronal Mass Ejection

Kinematics of coronal mass ejections between 2 and 30 solar radii

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