The flux-gap between bright and dark solar magnetic structures

• Published in: Astronomy and astrophysics (Berlin) Vol. 445; no. 1; pp. 337 - 340
• Main Authors: Puschmann, K. G., Wiehr, E.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences 01.01.2006
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; magnetic fields; Sun: activity; Speckles; Magnetic flux; Upper bound; Solar atmosphere; Magnetic structure; Solar flux; Magnetic fields; Sun: activity; Sun; Diameter
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361:20054049

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 $2.5\times10^{17}$ 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.