ON THE AREA EXPANSION OF MAGNETIC FLUX TUBES IN SOLAR ACTIVE REGIONS

We calculated the three-dimensional (3D) distribution of the area expansion factors in a potential magnetic field, extrapolated from the high-resolution Hinode/SOT magnetogram of the quiescent active region NOAA 11482. Retaining only closed loops within the computational box, we show that the distri...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal 2014-11, Vol.796 (1), p.1-15
Main Authors: Dudik, Jaroslav, Dzifcakova, Elena, Cirtain, Jonathan W
Format: Article
Language:English
Subjects:
Approximation
APPROXIMATIONS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COMPUTERIZED SIMULATION
CROSS SECTIONS
DISTRIBUTION
EXPANSION
EXTRAPOLATION
Flares
Flux
GAMMA RADIATION
MAGNETIC FIELDS
MAGNETIC FLUX
Mathematical analysis
NOAA
RESOLUTION
SOLAR CORONA
SUN
TELESCOPES
Three dimensional
THREE-DIMENSIONAL CALCULATIONS
Tubes
ULTRAVIOLET RADIATION
X RADIATION
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We calculated the three-dimensional (3D) distribution of the area expansion factors in a potential magnetic field, extrapolated from the high-resolution Hinode/SOT magnetogram of the quiescent active region NOAA 11482. Retaining only closed loops within the computational box, we show that the distribution of area expansion factors show significant structure. Loop-like structures characterized by locally lower values of the expansion factor are embedded in a smooth background. These loop-like flux tubes have squashed cross-sections and expand with height. The distribution of the expansion factors show an overall increase with height, allowing an active region core characterized by low values of the expansion factor to be distinguished. The area expansion factors obtained from extrapolation of the Solar Optical Telescope magnetogram are compared to those obtained from an approximation of the observed magnetogram by a series of 134 submerged charges. This approximation retains the general flux distribution in the observed magnetogram, but removes the small-scale structure in both the approximated magnetogram and the 3D distribution of the area expansion factors. We argue that the structuring of the expansion factor can be a significant ingredient in producing the observed structuring of the solar corona. However, due to the potential approximation used, these results may not be applicable to loops exhibiting twist or to active regions producing significant flares.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1088/0004-637X/796/1/20