Search Publications
Relation between the radial speed and theexpansion speed of coronal mass ejections
Schwenn, R.; Gonzalez, W. D.; Dal Lago, A.
We have selected 57 limb coronal mass ejections observed by LASCO during the period of January1997 to April 2001. We used the related EIT activity close to the limb to define these CMEs as "limbs". We measured the radial speed of the leading edge close to the center of these CMEs and the lateral expansion speed of the structures. Comparison of bot…
Coronal mass ejections: Initiation and detection
Gopalswamy, N.
Coronal mass ejections (CMEs) are large-scale magnetic structures expelled from the Sun due to MHD processes involving interaction between plasma and magnetic field in closed field regions. I provide a summary of the observational signatures and current models on CME initiation. I also discuss the multiwavelength signatures of CMEs, which have hel…
Properties of narrow coronal mass ejections observed with LASCO
Howard, R. A.; Gopalswamy, N.; Michalek, G. +1 more
We report the statistical properties of narrow coronal mass ejections (CMEs, angular width < 20°) withparticular emphasis on comparison with normal CMEs. We investigated 806 narrow CMEs from an online LASCO/CME catalog and found that (1) the fraction of narrow CMEs increases from 12% to 22% towards solar maximum, (2) during the solar maximum, t…
Soho observations relating to the association between flares and coronal mass ejections
Harrison, R. A.
Campaigns to investigate the solar coronal mass ejection (CME) onset have been run using the Solar andHeliospheric Observatory (SOHO) since 1996. These have included coronagraph and extreme-ultraviolet (EUV) disc imaging, along with magnetic mapping of the photosphere, in concert with EUV and UV spectroscopic observations. These campaigns have inc…
Energetic particle acceleration by coronal mass ejections
Kahler, S. W.
The current paradigm for the source of large, gradual solar energetic particle (SEP) events is that theyare accelerated in coronal/interplanetary shocks driven by coronal mass ejections (CMEs). Early studies established that there is a rough correlation between the logs of the CME speed and the logs of the SEP intensities. Here I review two topics…
Coronal mass ejection interaction and particle acceleration during the 2001 April 14 15 events
Kaiser, M. L.; Howard, R. A.; Gopalswamy, N. +1 more
Two successive solar energetic particle (SEP) events associated with fast and wide coronal mass ejections (CMEs) on 2001 April 14 and 15 are compared. The weak SEP event of April 14 associated with an 830 km/s CME and an M1.0 flare was the largest impulsive event of cycle 23. The April 15 event, the largest ground level event of cycle 23, was thre…
Search for a chromospheric resonator above sunspots
Kjeldseth-Moe, O.; Brekke, P.; Brynildsen, N. +2 more
We have recently observed thirteen sunspots, both with CDS on SOHO and TRACE. For each sunspot we investigate the oscillations in the chromosphere, transition region and corona. Above the umbra the power spectra show one dominant peak corresponding to a period of 3 minutes. The intensity oscillation amplitude increases with increasing temperature,…
Flare characteristics: Properties of eruptive and non-eruptive events and their associations
Culhane, J. L.; Harra, L. K.; Kay, H. R. M. +1 more
The complex: relationship between solar flares and coronal mass ejections is investigated using a comparison of flare parameters for a total of 69 ejective and non-ejective flares. In the case of solar flares which do not show mass ejection there seems to be a clear relationship between the peak intensity and duration, with higher intensity events…
On the sudden disappearances of solar filaments and their relationship with coronal mass ejections
Pojoga, S.; Huang, T. S.
Sudden disappearances of prominences/filaments were identified from the Prairie View Solar Observatory H α imagesand Meudon Observatory spectroheliograms for the period January 1, 2000 to March 31, 2000. Three classes of disappearances were considered for the purpose of this study: eruptive, quasi-eruptive and vanishing filaments. The H α events w…
How directions and helicity of erupted solar magnetic fields define geoeffectiveness of coronal mass ejections
Wang, Haimin; Yurchyshyn, Vasyl; Abramenko, Valentyna
In this study we report on the relationship between the projected speed of CMEs, measured at 20R from SOHO/LASCO images, and the hourly averaged magnitude of the southwardly directed magnetic field, B z, at the leading edge of interplanetary ejecta, as measured by the ACE magnetometer. We found that those CMEs that originate at the cent…