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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. Hirzberger21 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