Volume 599, March 2017
|Number of page(s)||10|
|Published online||14 March 2017|
Inference of the chromospheric magnetic field orientation in the Ca ii 8542 Å line fibrils
1 Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
2 Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
3 Institute for Solar Physics, Dept. of Astronomy, Stockholm University, Albanova University Center, 10691 Stockholm, Sweden
Received: 20 September 2016
Accepted: 15 December 2016
Context. Solar chromospheric fibrils, as observed in the core of strong chromospheric spectral lines, extend from photospheric field concentrations suggesting that they trace magnetic field lines. These images have been historically used as proxies of magnetic fields for many purposes.
Aims. Use statistical analysis to test whether the association between fibrils and magnetic field lines is justified.
Methods. We use a Bayesian hierarchical model to analyze several tens of thousands of pixels in spectro-polarimetric chromospheric images of penumbrae and chromospheric fibrils. We compare the alignment between the field azimuth inferred from the linear polarization signals through the transverse Zeeman effect and the direction of the fibrils in the image.
Results. We conclude that, in the analyzed fields of view, fibrils are often well aligned with the magnetic field azimuth. Despite this alignment, the analysis also shows that there is a non-negligible dispersion. In penumbral filaments, we find a dispersion with a standard deviation of ~ 16°, while this dispersion goes up to ~ 34° in less magnetized regions.
Key words: Sun: chromosphere / Sun: magnetic fields / sunspots / polarization
© ESO, 2017
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.