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Issue A&A
Volume 422, Number 3, August II 2004
Page(s) L63 - L66
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200400019



A&A 422, L63-L66 (2004)
DOI: 10.1051/0004-6361:200400019

Letter

Brightness and size of small-scale solar magnetic flux concentrations

E. Wiehr1, B. Bovelet1 and J. Hirzberger2

1  Universitäts-Sternwarte, Geismarlandstraße 11, 37083 Göttingen, Germany
    e-mail: ewiehr@uni-sw.gwdg.de
2  Institut für Geophysik, Astrophysik und Meteorologie, Universitätsplatz 5, 8010 Graz, Austria

(Received 13 April 2004 / Accepted 22 June 2004)

Abstract
The new 1 m Swedish Solar Telescope SST on La Palma allows to observe inter-granular G-band bright points (igBP) in solar active regions at an unprecedented spatial resolution. The igBP are reasonably assumed to be small-scale magnetic flux-concentrations. A sample of more than 1500 igBP shows tight relations of diameter and brightness in the G-band and in the continuum; it covers a diameter range of 100 km to 300 km, with a most frequent value near 160 km. Features larger than 300 km formerly reported, evidently result from insufficient spatial resolution; that upper diameter limit is close to the typical width of inter-granular lanes, and suggests a "gap" to small pores. The lack of igBP with sizes below 130 km is discussed not to arise from the finite spatial resolution of the 1 m telescope.


Key words: Sun: photosphere -- magnetic fields




© ESO 2004


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