Bibcode
Díaz Baso, C. J.; Martínez González, M. J.; Asensio Ramos, A.
Bibliographical reference
The Astrophysical Journal, Volume 822, Issue 1, article id. 50, pp. (2016).
Advertised on:
5
2016
Journal
Citations
7
Refereed citations
6
Description
Recent spectropolarimetric observations of active region filaments have
revealed polarization profiles with signatures typical of the strong
field Zeeman regime. The conspicuous absence in those observations of
scattering polarization and Hanle effect signatures was then pointed out
by some authors. This was interpreted as either a signature of mixed
“turbulent” field components or as a result of optical
thickness. In this article, we present a natural scenario to explain
these Zeeman-only spectropolarimetric observations of active region (AR)
filaments. We propose a two-component model, one on top of the other.
Both components have horizontal fields, with the azimuth difference
between them being close to 90°. The component that lies lower in
the atmosphere is permeated by a strong field of the order of 600 G,
while the upper component has much weaker fields, of the order of 10 G.
The ensuing scattering polarization signatures of the individual
components have opposite signs, so its combination along the line of
sight reduces—and even can cancel out—the Hanle signatures,
giving rise to an apparent Zeeman-only profile. This model is also
applicable to other chromospheric structures seen in absorption above
ARs.