In:
Publications of the Astronomical Society of Japan, Oxford University Press (OUP), Vol. 59, No. sp3 ( 2007-11-30), p. S649-S654
Abstract:
We observed small-scale magnetic-flux emergence in a sunspot moat region by the Solar Optical Telescope (SOT) aboard the Hinode satellite. We analyzed filtergram images observed at wavelengths of Fe 6302 Å, G band, and Ca II H. In Stokes$I$ images of Fe 6302 Å, emerging magnetic flux was recognized as dark lanes. In the G band, they showed to be their shapes almost the same as in Stokes$I$ images. These magnetic fluxes appeared as dark filaments in Ca II H images. Stokes$V$ images of Fe 6302 Å showed pairs of opposite polarities at footpoints of each filament. These magnetic concentrations were identified to correspond to bright points in G band/Ca II H images. From an analysis of time-sliced diagrams, we derived the following properties of emerging flux, which are consistent with those of previous studies: (1) Two footpoints separate each other at a speed of 4.2 kms$^{-1}$ during the initial phase of evolution, and decrease to about 1 kms$^{-1}$ 10 minutes later. (2) Ca II H filaments appear almost simultaneously with the formation of dark lanes in Stokes$I$ in an observational cadence of 2 minutes. (3) The lifetime of the dark lanes in the Stokes $I$ and G band is 8 minutes, while that of Ca filament is 12 minutes. An interesting phenomena was observed, that an emerging flux tube expanded laterally in the photosphere with a speed of 3.8 kms$^{-1}$. A discussion on the horizontal expansion of the flux tube is given with refernce to previous simulation studies.
Type of Medium:
Online Resource
ISSN:
0004-6264
,
2053-051X
DOI:
10.1093/pasj/59.sp3.S649
Language:
English
Publisher:
Oxford University Press (OUP)
Publication Date:
2007
detail.hit.zdb_id:
2206640-8
detail.hit.zdb_id:
2083084-1
SSG:
16,12
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