Stereoscopic Observations of Low Coronal Ejections With and Without CMEs

1. Stereoscopic Observations of Low Coronal Ejections With and Without CMEs N. V. Nittaa, J.-P. Wülsera, M. J. Aschwandena, J. R. Lemena, C. Leea,b a Lockheed Martin Solar andAstrophysics Laboratory b Palo Alto High School Poster ID: SH32A-0775 We study the relation of flare-associated ejections with CMEs in B-class and C-class flares that occurred in AR 10956. In some of the events, we have tried to follow the trajectory of the ejection using data from SECCHI EUVI on STEREO. The high cadence EUVI 171 Å images capture ejections and opening of overlying loops at the same time, but it is not clear from 304 Å observations alone which flares are associated with CMEs. Flare associated with a CME Flares in AR 10956 Before After Flare not associated with a CME The association of the flare with a CME is correlated with large-scale signatures in 195 Å images. Shown below are running difference images from EUVI-A. After Before The following sequence (19-May-2007) shows that 171Å high cadence observations are complementary to 304 Å (upper 304 Å, lower 171 Å difference). Signatures of dimming and waves in 304 Å images are small, but 171 Å images do not show the eruption to north. As in the poster SH32A-0768, we have made some attempt at triangulating eruptive filaments associated with CMEs. The software developed for tracing static coronal loops is used. But we still have not found the results compelling. Image plane (lower left), polar projection (upper left) and west limb projection (lower right). 19 May The speed referred to the highest point between time 3 and time 4 is 33 km/s (304 Å.) 1. 12:21:45, 2. 13:21:45, 3. 13:41:45, 4. 14:41:45 1. 12:41:30, 2. 12:51:30, 3. 12:54:00 20 May The speed referred to the highest point between time 2 and time 3 is 66 km/s (304 Å.) Conclusions 1. 05:11:45, 2. 05:21:45, 3. 05:31:45, 4. 05:41:45, 5. 05:51:45 1. 05:11:30, 2. 05:41:30, 3. 05:49:00 171 Å 304 Å • SECCHI EUVI data have allowed us to understand eruptions in 3-d. • We still heavily rely on anaglyph movies. • Although the triangulation technique used here are basically for loops, there may be areas for improvement that makes it applicable to filament eruptions. • Unlike coronal loops, filaments are not well represented as curves without thickness. • They change shape as they erupt. • Emission in the same line of sight contributes --> difference images may help. • In the coronal channels, filaments are sometimes seen both in absorption and emission, but other features in emission may not be indistinguishable.