Bibcode
DOI
Trujillo Bueno, Javier; Casini, Roberto; Landolfi, Marco; Landi Degl'Innocenti, Egidio
Bibliographical reference
The Astrophysical Journal, Volume 566, Issue 1, pp. L53-L57.
Advertised on:
2
2002
Journal
Citations
48
Refereed citations
35
Description
We demonstrate that the atomic alignment of the hyperfine-structure
components of the ground-level S1/2 of Na I and of the
upper-level P1/2 of the D1 line are practically
negligible for magnetic strengths B>10 G and virtually zero for
B>~100 G. This occurs independently of the magnetic field inclination
on the stellar surface (also, in particular, for vertical fields).
Consequently, the characteristic antisymmetric linear polarization
signature of the scattered light in the D1 line is
practically suppressed in the presence of magnetic fields larger than 10
G, regardless of their inclination. Remarkably, we find that the
scattering polarization amplitude of the D2 line increases
steadily with the magnetic strength, for vertical fields above 10 G,
while the contribution of the alignment to the polarization of the
D1 line rapidly decreases. Therefore, we suggest that
spectropolarimetric observations of the ``quiet'' solar chromosphere
showing significant linear polarization peaks in both D1 and
D2 cannot be interpreted in terms of one-component magnetic
field models, implying that the magnetic structuring of the solar
chromosphere could be substantially more complex than previously
thought.