Astronomy and Astrophysics – Astrophysics
Scientific paper
May 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002a%26a...386..646l&link_type=abstract
Astronomy and Astrophysics, v.386, p.646-652 (2002)
Astronomy and Astrophysics
Astrophysics
24
Sun: Magnetic Fields, Sun: Sunspots, Sun: Flares
Scientific paper
delta -groups generally develop in three different ways: eruption of a single complex active region, eruption of large satellite spots near a large older spot, or collision of spots of opposite polarity from different dipoles. In this paper, we present a rare observational result in which a delta -spot forms from rapid coalescence of two opposite magnetic features in a pre-existing delta -configuration. The white-light (WL) observations of this delta -spot in active region NOAA 9077 were performed by TRACE. The time-lapse movie of the co-aligned WL images shows that the whole active region was undergoing rapid disintegration and reconstruction on 11-17 July 2000. The preceding ({p}) and following ({f}) components of the delta -spot continue to grow in size, while the active region is in the decaying phase. Their proper motions are determined as a function of time using SOHO/MDI full-disk magnetograms. A major flare (3B/X5.7) erupted in the active region on 14 July. Initially, a relative shearing motion is visible between the {p} and {f} spots on this day. About two hours before the major flare, the shearing motion suddenly stops and the velocities change significantly. The ribbons of the flare are located just outside of the delta -configuration. An interesting finding is the sign reversal of the helicity of the {f} spot also just 2 hours before the flare. The delta -spot obviously separates after the flare. Our results clearly demonstrate that helicity reversal in magnetic features of a delta -configuration is likely to destabilize the compact structure, as well as to re-organize the magnetic field configuration, and, hence, is important for the rapid disintegration of a delta -spot during major flares. A model is presented to explain why a spot can change its chirality.
Liu Ya-Ying
Zhang Qing-Hong
No associations
LandOfFree
Analysis of a delta spot 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 Analysis of a delta spot, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Analysis of a delta spot will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1716743