Reduced Microwave Brightness Temperature in a Sunspot Atmosphere due to Open Magnetic Fields
Abstract
Motivated by dark coronal lanes in SOHO / EIT 284 {\AA} EUV observations we construct and optimize an atmosphere model of the AR 8535 sunspot by adding a cool and dense component in the volume of plasma along open field lines determined using the Potential Field Source Surface (PFSS) extrapolation. Our model qualitatively reproduces the observed reduced microwave brightness temperature in the northern part of the sunspot in the VLA observations from 13 May 1999 and provides a physical explanation for the coronal dark lanes. We propose application of this method to other sunspots with such observed dark regions in EUV or soft X-rays and with concurrent microwave observations to determine the significance of open field regions. The connection between open fields and the resulting plasma temperature and density change is of relevance for slow solar wind source investigations.
Keywords
Cite
@article{arxiv.2102.05476,
title = {Reduced Microwave Brightness Temperature in a Sunspot Atmosphere due to Open Magnetic Fields},
author = {A. Vrublevskis and B. I. Ryabov and S. M. White},
journal= {arXiv preprint arXiv:2102.05476},
year = {2021}
}
Comments
26 pages, 12 figures. [v1] replaced to include journal reference after publication. This preprint has not undergone peer review or any post-submission improvements or corrections. The Version of Record of this article is published in Solar Physics, and is available online at https://doi.org/10.1007/s11207-021-01891-5