SHINE SEP Campaign Events: Long-term development of solar corona in build-up to the SEP events of 21 April 2002 and 24 August 2002 A. J. Coyner, D. Alexander, A. G. Daou, R Liu, Rice University SHINE 2004 Workshop June 27-July 2, 2004 The SEP signatures of the solar flares occurring on 21 Apr 2002 and 24 Aug 2002 show marked differences in their compositions above the 10 MeV/nucleon yet at the Sun, the events themselves show very little difference in either their hard X-ray chromospheric emission or their coronal signatures. In this paper, we investigate whether the two active regions demonstrated notably different coronal development as they progressed from disk center to the limb prior to each of the events they spawned. We utilize TRACE, EIT, and LASCO data to map out the coronal activity, connectivities, and heating of these active regions in the seven day period prior to the events in question.

Overview We present a detailed look at the coronal structure and activity for a week prior to each of the SHINE campaign events on 21 Apr 2002 and 24 Aug 2002 using EIT and TRACE EUV data. We pay particular attention to large-scale connections to other active regions, regions of apparently open magnetic field, and transient activity in the active regions Using data from LASCO, we compare the production of CME’s for each active region in terms of both number and CME speed

NOAA Active Region Maps Figure 1: NOAA Active Region Maps for the needed time periods. These are provided for reference as a number of active regions are referred to in this poster particularly AR 9906 and AR 0069 which are the active regions. Images obtained from the University of Hawaii Institute for Astronomy

EIT and TRACE Comparisons In our observations of the EIT and TRACE data for these time periods, we note a number of similarities and differences in the appearance of coronal structures surrounding the active regions. We focus on structures such as: –Large-scale connections between neighboring active regions –Evidence for areas of open field lines –Coronal response to flare events –Structural differences within the active regions We track these features and note changes and development as the active region proceeds toward the west limb.

Large scale connections between active regions APRIL AR9906 shows a series of loop structures emerging from the eastern edge of 9906 and connecting to A few loop structures become apparent connecting AR 9906 with 9902 As AR 9906 proceeds toward the limb the connections between AR 9906 and 9902 intensify greatly while connections to 9907 become less evident. AUGUST In the August data, the connections between active regions are shorter in length but appear to be more numerous As AR 0069 progresses to the limb only the connections to AR 0067 persist. This connection appears to weaken as time progresses as well. COMPARISON Both active regions show large- scale connections to other regions August corona is more complex with AR0069 displaying magnetic connections to several nearby regions. Figure 2: EIT image from April 15, 2002 and April 20, 2002 illustrating the connections between AR 9906 and AR 9907 and AR 9902 to the northwest Figure 3: EIT image from August 19,2002 and August 23, 2002 showing clear connection between AR 0069, AR 0067,AR 0068, and AR

Evidence of open magnetic field lines and coronal holes In the EIT images for active region 9906 there appears a large coronal hole to the south of the active region 9906 Studies of the magnetic field evolution (see poster by Liu et al.) show numerous open field lines in this region During the August events, no such dark regions appear This is consistent with the limited number of open field lines during the August events. (see poster by Liu et al.) A similar coronal hole exists to north and east. A Figure 4: A) EIT image from 15 April 2002 showing a large coronal hole to the south of AR 9906 and a smaller coronal hole to the north. (red boxes). B) EIT images from 19 August 2002which does not show as strong evidence. A B

TRACE Observations of AR 9906 Active Region 9906 shows a tendency to have significant loop structures Early TRACE images indicate very limited activity with only a few faint structures outlining the region. As the active region moves toward the limb, l loop structures proliferate the region and intensify also appearing to lengthen as time passes. AR 9906 appears to be a much smaller active region spatially than its August counterpart (AR 0069) Figure 5: Selected images from TRACE 195 A for AR As the time progresses, many bright loops emerge from the active region.

TRACE Observations of AR 0069 TRACE data pictured left are selected 195 A images from the time period August 20-24, During the initial days of our analysis, smaller loop structures such as those shown in figure 7a developed Later in the data, many much longer loop structures such as those shown in figure 7c dominate the active region structure. The loops that develop later on have a much longer spatial extent than those seen in the April data Figure 6: Selected TRACE 195 A images depicting the variety of structures encountered within AR 9906 C A D B

CME Statistics April 14-21, 2002 Number of CME’s: 48 [49] Mean Speed (km/s): 472 [511] Standard Dev. (km/s): 207 [342] Max Speed(km/s): 1218 [2409] August 17-24, 2002 Number of CME’s: 54 [55] Mean Speed(km/s): 549[573] Standard Dev.(km/s): 269 [321] Max Speed(km/s ): 1170 [ 1878] Our focus for this analysis in to determine any potential differences in coronal behavior leading to the campaign events. For these CME statistics the values in green represent the values without the campaign events. The blue series includes the campaign events. By excluding the campaign events, which in both cases have speeds which far exceed any other CME during the week of evolution, we can more accurately assess the CME productivity leading up to the campaign events. These statistics take into account all CME’s for the time ranges above which possessed a valid linear fit speed. Further analysis into the speed distributions for each of these time ranges in shown below.

CME Speed Histogram Figure 1 shows a comparison of the speed distributions for the April (yellow) and August (blue) time periods The campaign events themselves (shown with arrows ) seem to distort the distribution as a result of high speed. Below, we include new statistics looking at the CME’s preceding the campaign events only Figure 7: Comparative histogram of April (yellow) and August (blue) CME’s binned by speed.

Summary and Conclusions The coronal development of the sun (and particularly active regions 9906 and 0069) shows distinct differences between the April 2002 and August 2002 evolution. Both active regions show evidence of large-scale connections to neighboring active regions. The connections from AR 0069 indicate a more complex coronal development involving four interconnected active regions The EIT Images of the area surrounding AR 9906 indicate the existence of two coronal holes. This existence is consistent with the open field lines found near AR 9906 The TRACE images for the two active regions show marked differences in structure –AR 9906 shows a number of small loops dominating the structure the structure throughout –AR 0069 shows longer loop structures at later times in its evolution but also shows increased flare activity in comparison Analysis of the CME’s recorded by LASCO show increased global activity both in number and average speed during the August timeframe

Acknowledgements We would like to thank the SHINE group for providing student support for Aaron Coyner, Antoun Daou, and Rui Liu