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Interplanetary acceleration of coronal mass ejections
St. Cyr, O. C.; Kaiser, M. L.; Gopalswamy, N. +3 more
Using an observed relation between speeds of CMEs near the Sun and in the solar wind, we determine an “effective” acceleration acting on the CMEs. We found a linear relation between this effective acceleration and the initial speed of the CMEs. The acceleration is similar to that of the slow solar wind in magnitude. The average solar wind speed na…
Coronal dimmings and energetic CMEs in April-May 1998
Thompson, B. J.; Delaboudinière, J. -P.; Nitta, N. +2 more
We have analyzed the coronal dimmings for seven fast (> 600 km/s) coronal mass ejections (CMEs) occurring between 23 April and 9 May which were associated with flares from NOAA active region (AR) 8210. Each of these CMEs had at least one group of interplanetary radio bursts associated with them. These dimming regions were identified by their st…
SOHO and radio observations of a CME shock wave
St. Cyr, O. C.; Romoli, M.; Gopalswamy, Nat +7 more
A 1200 km s-1 Coronal Mass Ejection was observed with the SOHO instruments EIT, LASCO and UVCS on June 11, 1998. Simultaneously, Type II radio bursts were observed with the WAVES experiment aboard the Wind spacecraft at 4 MHz and by ground-based instruments at metric wavelengths. The density in the shock wave implied by the higher frequ…
Radio-rich solar eruptive events
Thompson, B. J.; Kaiser, M. L.; Burlaga, L. F. +6 more
We report on the analysis of a large number of solar eruptive events that produced radio emission in the dekameter-hectometric (DH) radio window (1-14 MHz), newly opened by the Wind/WAVES experiment. The distinguishing characteristics of coronal mass ejections (CMEs) associated with the DH type II radio bursts are larger-than-average width and spe…
Monitoring solar activity on the far side of the sun from sky reflected Lyman α radiation
Bertaux, Jean-Loup; Lallement, Rosine; Schmidt, Walter +3 more
Solar active regions are known to be brighter in Lyman α radiation than the quiet sun. Accordingly, they illuminate more H atoms in interplanetary space through resonance scattering. As we show here, this excess of illumination related to active regions is clearly seen in full-sky Lyman α maps recorded by the SWAN instrument on board SOHO, includi…
Change in photospheric magnetic flux during coronal mass ejections
Gopalswamy, Nat; DeForest, Craig; Lara, Alejandro
We report on the variations of photospheric magnetic flux during coronal mass ejections (CMEs). Using magneograms from the SOHO/MDI instrument, we have computed the magnetic flux of 7 active regions and one disappearing filament region associated with CMEs. When we plotted the flux versus time over a period of few days before, during and after the…
Coronal mass ejections detected in solar mean magnetic field
Boberg, Fredrik; Lundstedt, Henrik
One minute resolution solar mean magnetic field sequences during 74 coronal mass ejection events are analyzed using wavelet transforms. A significant fraction of the resulting wavelet power spectra shows a characteristic peak at the time of the coronal mass ejection. With an average period of 13 minutes, the signature in the solar mean field is mo…