Ab Initio Active Region Formation
Abstract
The tachocline is not necessary to produce active regions with their global properties. Dynamo action within the convection zone can produce large scale reversing polarity magnetic fields as shown by ASH code and Charboneau et al simulations. Magneto-convection acting on this large scale field produces Omega-loops which emerge through the surface to produce active regions. The field first emerges as small bipoles with horizontal field over granules anchored in vertical fields in the intergranular lanes. The fields are quickly swept into the intergranular lanes and produce a mixed polarity "pepper and salt" pattern. The opposite polarities then migrate toward separate unipolar regions due to the underlying large scale loop structure. When sufficient flux concentrates, pores and sunspots form. We will show movies of magneto-convection simulations of the emerging flux, its migration, and concentration to form pores and spots, as well as the underlying magnetic field evolution. In addition, the same atmospheric data has been used as input to the LILIA Stokes Inversion code to calculate Stokes spectra for the Fe I 630 nm lines and then invert them to determine the magnetic field. Comparisons of the inverted field with the simulation field shows that small-scale, weak fields, less than 100 G, can not be accurately determined because of vertical gradients that are difficult to match in fitting the line profiles. Horizontal smoothing by telescope diffraction further degrades the inversion accuracy.
- Publication:
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American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22141502S