Sunspot Rotation, Eruptive Flare Energetics And Flux Rope Helicity: Topology Matters.
Abstract
We study the role of rotation in the flare energy and helicity budget of two active regions: NOAA 10486 and NOAA 10759. Using MDI and TRACE observations of photospheric magnetic and velocity fields in those active regions we build a topological model of their three-dimensional coronal magnetic field. In both active regions a fast rotating sunspot is observed. We apply a method for including such rotation in the framework of the minimum current corona model (MCC, Longcope 1996) to the buildup of energy and helicity associated with the X17.2 eruptive flare on 2003 October 28 (the Halloween flare) and M8.0 eruptive flare on 2005 May 13. We find that including the sunspot rotation in the model changes the total flare thermal energy and flux rope helicity by only 10% for the Halloween flare, but by more than 200% for the 2005 May 13 flare. While for the Halloween flare shearing motions alone store sufficient energy and helicity to account for the flare energetics and ICME helicity content within their observational uncertainties, for the 2005 May 13 flare it is the rotation that dominates. We demonstrate that the relative importance of shearing and rotation in those two flares depends critically on their location within the parent active region topology.
- Publication:
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American Astronomical Society Meeting Abstracts #216
- Pub Date:
- May 2010
- Bibcode:
- 2010AAS...21632003K