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Issue A&A
Volume 445, Number 1, January I 2006
Page(s) 337 - 340
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20054049



A&A 445, 337-340 (2006)
DOI: 10.1051/0004-6361:20054049

The flux-gap between bright and dark solar magnetic structures

K. G. Puschmann and E. Wiehr

Institut für Astrophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
    e-mail: [kgp;ewiehr]@astro.physik.uni-goettingen.de

(Received 21 March 2005 / Accepted 1 September 2005)

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 $2.5\times10^{17}$ 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.


Key words: Sun: activity -- magnetic fields




© ESO 2005


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