A Search for Pre-Emergence Helioseismic Signatures of Active Regions
Abstract
Helioseismology can be an important tool for understanding the formation of active regions. As a first step towards this goal, we have carried out a search for statistically significant helioseismic precursors of active region emergence. We used an automatic method to determine the time of emergence based on the NOAA/NGDC active region catalog and MDI/SOHO 96 minute magnetograms. Using GONG data, we applied helioseismic holography to 107 pre-emergence active regions and a control sample of 107 regions where no active region was present. We found some significant and surprising differences between our samples in both quantities determined from helioseismology and from surface magnetic fields. However, we do not see a clear signature of emergence when considering individual active regions. The results of this investigation may shed some light on the mechanism responsible for flux emergence, and certainly illustrate the care which must be taken in conducting such an investigation.
This work was supported by NASA contract NNH07CD25C.- Publication:
-
American Astronomical Society Meeting Abstracts #220
- Pub Date:
- May 2012
- Bibcode:
- 2012AAS...22020510B