CAOSP abstracts, Volume: 32, No.: 2, year: 2002
- Author(s): Badalyan, O.G.; Obridko, V.N.; Sýkora, J.
- Journal: Contributions of the Astronomical Observatory Skalnaté Pleso, vol. 32, no. 2, p. 175-189.
- Date: 10/2002
- Title: Polarization in the 530.3nm emission line and coronal magnetic field structure
- Keyword(s): coronal green line, polarization characteristics, coronal magnetic field
- Pages: 175 -- 189
Abstract:
To clarify the possible influence of the coronal magnetic field
on the degree of polarization p, direction of polarization β,
and line intensity I_λ measured during the 11 July 1991 total
solar eclipse, we have compared these quantities with different field
parameters. The structure of the coronal magnetic field on the eclipse
day was calculated using potential approximation. The relation of p and
I_λ as measured at 1.2 R_Sun from the centre of the solar
disk to the strength of the magnetic field and its different components is
discussed in detail. It is found that the points pertinent to the
large-scale coronal structures of different morphological (physical)
types (high-latitude streamers, bright equatorial regions, regions in the
vicinity of coronal holes, etc.) form isolated, not overlapping
clusters of points on the B -- p, B -- β and B -- log I_λ
diagrams. Two classes of objects are distinct in these
diagrams. The first class comprises of high-latitude streamers in which
the degree of polarization increases with decreasing B. The second class
is represented by coronal condensations, moderately active equatorial
regions, and coronal holes. In the objects of this class, the magnetic
field strength is approximately three times as large as in the streamers,
and the degree of polarization depends only weakly on B.
It is shown that p, I_λ and β display a noticeable
relationship with the indices Q_1 and Q_2, which we introduced to
characterize the complexity (degree of inhomogeneity) of the magnetic
field at any given point in the solar corona. In fact, Q_1 and Q_2
represent the absolute and relative deviations of B from its mean
value measured in the neighbourhood of a given point.
The results of our investigation suggest that we are dealing with the
direct influence of the magnetic field on the generation of the polarized
radiation in the λ 530,3nm emission line. One can expect,
therefore, that the investigation of polarization characteristics
would provide a useful method for determining the magnetic field in the
solar corona.
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