Volume 644, December 2020
|Number of page(s)||9|
|Section||The Sun and the Heliosphere|
|Published online||03 December 2020|
The magnetic fine structure of the Sun’s polar region as revealed by Sunrise
Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
2 School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701, Republic of Korea
Accepted: 29 September 2020
Context. Polar magnetic fields play a key role in the solar magnetic cycle and they are the source of a significant portion of the interplanetary magnetic field. However, observations of the poles are challenging and hence our understanding of the polar magnetic environment is incomplete.
Aims. We deduce properties of small-scale magnetic features in the polar region using high-resolution data and specifically aim to determine the flux per patch above which one magnetic polarity starts to dominate over the other.
Methods. We study the high spatial resolution, seeing-free observations of the north solar polar region, obtained with the IMaX instrument on-board the balloon-borne SUNRISE observatory during June 2009, at the solar activity minimum. We performed inversions of the full Stokes vector recorded by IMaX to retrieve atmospheric parameters of the Sun’s polar region, mainly the temperature stratification and the magnetic field vector.
Results. We infer kilo-Gauss (kG) magnetic fields in patches harbouring polar faculae, without resorting to a magnetic filling factor. Within these patches we find the maxima of the magnetic field to be near the dark narrow lanes, which are shifted towards the disc centre side in comparison to the maxima in continuum intensity. In contrast, we did not find any fields parallel to the solar surface with kG strengths. In addition to the kG patches, we found the polar region to be covered in patches of both polarities, which have a range of sizes. We find the field strength of these patches to increase with increasing size and flux, with the smaller patches showing a significant dispersion in field strength. The dominating polarity of the north pole during this phase of the solar cycle is found to be maintained by the larger patches with fluxes above 2.3 × 1017 Mx.
Key words: Sun: magnetic fields / Sun: faculae / plages
© A. Prabhu et al. 2020
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Open Access funding provided by Max Planck Society.
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.