The flux-gap between bright and dark solar magnetic structures
Abstract
The upper size limit of solar small-scale magnetic flux concentrations ("G-band bright points", BP) is reconsidered from speckle-reconstructed images taken at the 1-m SST on La Palma. The size-histogram shows a sharp drop towards 250 km diameter, variation of the noise filter threshold diminishes that value due to segmentation of the elongated structures. A further artificial segmentation of still elongated (i.e. not round) BP indicates that the upper limit may well be below 200 km diameter, corresponding to a flux smaller than 2.5×1017 Mx which is more than 40 times smaller than that of smallest dark (mini-) pores. BP with diameters of 130 km would already yield to a flux gap of two orders of magnitude. The drop of BP numbers between the histogram maximum and the 90 km resolution limit achieved is found to depend on the low-pass filtering and is thus probably virtual. Higher spatial resolution data will still increase the flux gap between bright and dark solar magnetic flux concentrations which might be a signature of differently deep rooting in the solar atmosphere.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 2006
- DOI:
- 10.1051/0004-6361:20054049
- Bibcode:
- 2006A&A...445..337P
- Keywords:
-
- Sun: activity;
- magnetic fields