Solar off-limb emission of the OI 7772 \AA\ line
Abstract
The aim of this paper is to understand the formation of the OI line at 7772 \AA\ in the solar chromosphere. We used SST/CRISP observations to observe OI 7772 \AA\ in several places around the solar limb. We compared the observations with synthetic spectra calculated with the RH code in the one-dimension spherical geometry mode. New accurate hydrogen collisional rates were included for the RH calculations. The observations reveal a dark gap in the lower chromosphere, which is caused by variations in the line opacity as shown by our models. The lower level of the 7772 \AA\ transition is populated by a downward cascade from the continuum. We study the effect of Lyman- pumping and hydrogen collisions between the triplet and quintet system in OI. Both have a small but non-negligible influence on the line intensity.
Cite
@article{arxiv.1705.06459,
title = {Solar off-limb emission of the OI 7772 \AA\ line},
author = {Hiva Pazira and D. Kiselman and J. Leenaarts},
journal= {arXiv preprint arXiv:1705.06459},
year = {2017}
}
Comments
9 pages, 12 figures, Accepted for publication in A&A