Magnetic Helicity Change Rate Associated with X-Class and M-Class Flares

We investigate the total helicity change rate of active regions during the time period of three X-class and five M-class flares using MDI full-disk magnetograms which are sufficient to calculate the advection and the shuffling terms. Two out of three regions with X-class flares show a significant ch...

Full description

Saved in:
Bibliographic Details
Published in:Solar physics 2004-12, Vol.225 (2), p.311-324
Main Authors: Hartkorn, Klaus, Wang, Haimin
Format: Article
Language:English
Subjects:
Investigations
Solar physics
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We investigate the total helicity change rate of active regions during the time period of three X-class and five M-class flares using MDI full-disk magnetograms which are sufficient to calculate the advection and the shuffling terms. Two out of three regions with X-class flares show a significant change in the helicity change rate, while none of the five active regions with an associated M-class flare shows this behavior. A closer investigation of the active regions associated with a helicity change reveals certain peculiarities that point to an artificial signal due to the magnetic reversal effect. This is supported by the fact that a simulation of the reversal effect reproduces the same shape of the helicity signal, although with an amplitude one magnitude lower. We investigate active regions with no flaring activity and determine the fluctuations of the helicity change rate due to instrumental effects to be 12 × 10^sup 40^ Mx^sup 2^ h^sup -1^.[PUBLICATION ABSTRACT]
ISSN:0038-0938
1573-093X
DOI:10.1007/s11207-004-5699-y