Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly

Details Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly

2012-02-17

arxiv.org/abs/1202.4001v1

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

15 pages text, 7 figures in main body, 5 Appendix figures

Scientific paper

A well known behavior of EUV light curves of discrete coronal loops is that the peak intensities of cooler channels or spectral lines are reached at progressively later times than hotter channels. This time lag is understood to be the result of hot coronal loop plasma cooling through these lower respective temperatures. However, loops typically comprise only a minority of the total emission in active regions. Is this cooling pattern a common property of active region coronal plasma, or does it only occur in unique circumstances, locations, and times? The new SDO/AIA data provide a wonderful opportunity to answer this question systematically for an entire active region. We measure the time lag between pairs of SDO/AIA EUV channels using 24 hours of images of AR 11082 observed on 19 June 2010. We find that there is a time-lag signal consistent with cooling plasma, just as is usually found for loops, throughout the active region including the diffuse emission between loops for the entire 24 hour duration. The pattern persists consistently for all channel pairs and choice of window length within the 24 hour time period, giving us confidence that the plasma is cooling from temperatures of greater than 3 MK, and sometimes exceeding 7 MK, down to temperatures lower than ~ 0.8 MK. This suggests that the bulk of the emitting coronal plasma in this active region is not steady; rather, it is dynamic and constantly evolving. These measurements provide crucial constraints on any model which seeks to describe coronal heating.

Affiliated with

Also associated with

No associations

Rating

Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-32146