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On the relation between penumbral intensity and flow filaments
Author(s) -
Schlichenmaier R.,
Bellot Rubio L. R.,
Tritschler A.
Publication year - 2005
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200410394
Subject(s) - penumbra , sunspot , physics , protein filament , astrophysics , flow (mathematics) , optics , mechanics , chemistry , magnetic field , medicine , biochemistry , ischemia , quantum mechanics , cardiology
Taking advantage of high spatial (≈0.5 arcsec) and high spectral ( λ/δλ = 250 000) resolution observations obtained with the 2D spectrometer TESOS, we analyze a sunspot located at a heliocentric angle of 23°. We elaborate on the issue of a correlation between dark filaments and the Evershed flow in sunspot penumbrae. Controversies on the existence of such a correlation are resolved: It varies from the inner to the outer penumbra, from the center‐side to the limb‐side penumbra, and depends on the length of the trace which is used to perform the correlation. The flow map exhibits flow filaments in the center‐side penumbra while the red‐shifted limb‐side penumbra does not show filamentary fine‐structure. High correlation coefficients, | C | ≈ 0.9 are only found if small scales, i.e. short traces cutting individual features are considered. C is positive in the inner center and limb‐side penumbra, and tends to be negative in the outer penumbra. Our results imply that the Evershed flow is present in bright and dark filaments. In individual cases we find that bright and dark intensities are connected by a flow filament supporting the moving tube model for the penumbral fine structure. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)