Case Study of a Magnetic Transient in NOAA 11429 Observed by SDO/HMI during the M7.9 Flare on 2012 March 13
Abstract
NOAA 11429 was the source of an M7.9 X-ray flare at the western solar limb (N18° W63°) on 2012 March 13 at 17:12 UT. Observations of the line-of-sight magnetic flux and the Stokes I and V profiles from which it is derived were carried out by the Solar Dynamics Observatory Helioseismic and Magnetic Imager (SDO/HMI) with a 45 s cadence over the full disk, at a spatial sampling of 0.''5. During flare onset, a transient patch of negative flux can be observed in SDO/HMI magnetograms to rapidly appear within the positive polarity penumbra of NOAA 11429. We present here a detailed study of this magnetic transient and offer interpretations as to whether this highly debated phenomenon represents a "real" change in the structure of the magnetic field at the site of the flare, or is instead a product of instrumental/algorithmic artifacts related to particular SDO/HMI data reduction techniques.
- Publication:
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The Astrophysical Journal
- Pub Date:
- December 2013
- DOI:
- 10.1088/0004-637X/778/2/175
- Bibcode:
- 2013ApJ...778..175H
- Keywords:
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- line: profiles;
- Sun: flares;
- Sun: magnetic fields;
- Sun: photosphere