Bibcode
DOI
Uitenbroek, H.; Miller-Ricci, E.; Asensio Ramos, A.; Trujillo Bueno, J.
Referencia bibliográfica
The Astrophysical Journal, Volume 604, Issue 2, pp. 960-968.
Fecha de publicación:
4
2004
Revista
Número de citas
11
Número de citas referidas
9
Descripción
We investigate the possibility of measuring magnetic field strength in
G-band bright points through the analysis of Zeeman polarization in
molecular CH lines. To this end we solve the equations of polarized
radiative transfer in the G band through a standard plane-parallel model
of the solar atmosphere with an imposed magnetic field and through a
more realistic snapshot from a simulation of solar magnetoconvection.
This region of the spectrum is crowded with many atomic and molecular
lines. Nevertheless, we find several instances of isolated groups of CH
lines that are predicted to produce a measurable Stokes V signal in the
presence of magnetic fields. In part this is possible because the
effective Landé factors of lines in the stronger main branch of
the CH A2Δ-X2Π transition tend to zero
rather quickly for increasing total angular momentum J, resulting in a
Stokes V spectrum of the G band that is less crowded than the
corresponding Stokes I spectrum. We indicate that, by contrast, the
effective Landé factors of the R and P satellite subbranches of
this transition tend to +/-1 for increasing J. However, these lines are
in general considerably weaker and do not contribute significantly to
the polarization signal. In one wavelength location near 430.4 nm, the
overlap of several magnetically sensitive and nonsensitive CH lines is
predicted to result in a single-lobed Stokes V profile, raising the
possibility of high spatial resolution narrowband polarimetric imaging.
In the magnetoconvection snapshot we find circular polarization signals
of the order of 1%, prompting us to conclude that measuring magnetic
field strength in small-scale elements through the Zeeman effect in CH
lines is a realistic prospect.