scholarly journals A catalog of white light coronal mass ejections observed by the SOHO spacecraft

2004 ◽  
Vol 109 (A7) ◽  
Author(s):  
S. Yashiro
Keyword(s):  
White Light ◽  
Coronal Mass Ejections ◽  
Soho Spacecraft

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

scholarly journals Clark Lake Radio Observations of Coronal Mass Ejections

1990 ◽  
Vol 142 ◽  
pp. 495-500
Author(s):  
N. Gopalswamy
Keyword(s):  
White Light ◽  
Coronal Mass Ejections ◽  
The Sun ◽  
Type Ii ◽  
Radio Observations ◽  
Magnetic Structures ◽  
Effect Relationship ◽  
Positional Analysis ◽  
Type Iv ◽  
Nonthermal Particles

We review some recent studies of mass ejections from the Sun using 2-D imaging observations of the Clark Lake multifrequency radioheliograph. Radio signatures of both fast and slow coronal mass ejections (CMEs) have been observed using the Clark Lake radioheliograph. Using temporal and positional analysis of moving type IV and type II bursts, and white light CMEs we find that the type II's and CMEs need not have a direct cause and effect relationship. Instead, the type II seems to be generated by a “decoupled shock”, probably due to an associated flare. The moving type IV burst requires nonthermal particles trapped in magnetic structures associated with the CME. Since nonthermal particles can be generated independent of the speed of CMEs, moving type IV bursts need not be associated only with fast CMEs. Specific examples are presented to support these views.

The magnetic flux rope structure of coronal mass ejections – 2021 Julius Bartels Medal Lecture at vEGU

2021 ◽  
Author(s):  
Volker Bothmer
Keyword(s):  
Magnetic Flux ◽  
White Light ◽  
Coronal Mass Ejections ◽  
Large Scale ◽  
Neutral Line ◽  
Source Region ◽  
Flux Rope ◽  
Magnetic Clouds ◽  
Small Scale ◽  
Magnetic Flux Rope

<div> <p><span>Magnetic clouds are transient solar wind flows in the interplanetary medium with smooth rotations of the magnetic field vector and low plasma beta values. The analysis of magnetic clouds identified in the data of the two Helios spacecraft between 0.3 and 1 AU showed that they can be interpreted to first order by force-free, large-scale, cylindrical magnetic flux tubes. A close correlation of their occurrences was found with disappearing filaments at the Sun. The magnetic clouds that originated from the northern solar hemisphere showed predominantly left-handed magnetic helicities and the ones from the southern hemisphere predominantly right-handed ones. They were often preceded by an interplanetary shock wave and some were found to be directly following a coronal mass ejection towards the Helios spacecraft as detected by the Solwind coronagraph on board the P78-1 satellite. With the SOHO mission unprecedented long-term observations of coronal mass ejections (CMEs) were taken with the LASCO coronagraphs, with a spatial and time resolution that allowed to investigate their internal white-light fine structure. With complementary photospheric and EUV observations from SOHO, CMEs were found to arise from pre-existing small scale loop systems, overlying regions of opposite magnetic polarities. From the characteristic pattern of their source regions in both solar hemispheres, a generic scheme was presented in which their projected white-light topology depends primarily on the orientation and position of the source region’s neutral line on the solar disk. Based on this interpretation the graduated cylindrical shell method was developed, which allowed to model the electron density distribution of CMEs as 3D flux ropes. This concept was validated through stereoscopic observations of CMEs taken by the coronagraphs of the SECCHI remote sensing suite on board the twin STEREO spacecraft. The observations further revealed that the dynamic near-Sun evolution of CMEs often leads to distortions of their flux rope structure. However, the magnetic flux rope concept of CMEs is today one of the fundamental methods in space weather forecasts. With the Parker Solar Probe we currently observe for the first time CMEs in-situ and remotely at their birthplaces in the solar corona and can further unravel their origin and evolution from the corona into the heliosphere. This lecture provides a state-of-the-art overview on the magnetic structure of CMEs and includes latest observations from the Parker Solar Probe mission.</span></p> </div>

scholarly journals BRIGHT RAY-LIKE FEATURES IN THE AFTERMATH OF CORONAL MASS EJECTIONS: WHITE LIGHT VERSUS ULTRAVIOLET SPECTRA

2013 ◽  
Vol 766 (1) ◽  
pp. 65 ◽  
Author(s):  
A. Ciaravella ◽  
D. F. Webb ◽  
S. Giordano ◽  
J. C. Raymond
Keyword(s):  
White Light ◽  
Coronal Mass Ejections ◽  
Ultraviolet Spectra

scholarly journals The Structure of Solar Coronal Mass Ejections in the Extreme-Ultraviolet Passbands

2020 ◽  
Author(s):  
Hongqiang Song
Keyword(s):  
Magnetic Field ◽  
White Light ◽  
Coronal Mass Ejections ◽  
Extreme Ultraviolet ◽  
Leading Edge ◽  
Low Density ◽  
The Core ◽  
Part Structure ◽  
Density Zone ◽  
Solar Coronal

<p>So far, most studies on the structure of coronal mass ejections (CMEs) are conducted through white-light coronagraphs, which demonstrate about one third of CMEs exhibit the typical three-part structure in the high corona (e.g., beyond 2 Rs), i.e., the bright front, the dark cavity and the bright core. In this presentation, we address the CME structure in the low corona (e.g., below 1.3 Rs) through extreme-ultraviolet (EUV) passbands and find that the three-part CMEs in the white-light images can possess a similar three-part appearance in the EUV images, i.e., a leading edge, a low-density zone, and a filament or hot channel. The analyses identify that the leading edge and the filament or hot channel in the EUV passbands evolve into the front and the core later within several solar radii in the white-light passbands, respectively. What's more, we find that the CMEs without obvious cavity in the white-light images can also exhibit the clear three-part appearance in the EUV images, which means that the low-density zone in the EUV images (observed as the cavity in white-light images) can be compressed and/or transformed gradually by the expansion of the bright core and/or the reconnection of magnetic field surrounding the core during the CME propagation outward. Our study suggests that more CMEs can possess the clear three-part structure in their early eruption stage. The nature of the low-density zone between the leading edge and the filament or hot channel is discussed.</p>

The correspondence of EUV and white light observations of coronal mass ejections with SOHO EIT and LASCO

1999 ◽  
pp. 31-46 ◽  
Author(s):  
B. J. Thompson ◽  
O. C. St. Cyr ◽  
S. P. Plunkett ◽  
J. B. Gurman ◽  
N. Gopalswamy ◽  
...  
Keyword(s):  
White Light ◽  
Coronal Mass Ejections
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