Study of the Green Coronal Line with Altitude from Out-of-Eclipse Observations during Solar Cycle 24

• Published in: Cosmic research Vol. 61; no. 2; pp. 133 - 141
• Main Authors: Guseva, S. A., Shramko, A. D.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-04-2023; Springer Nature B.V
• Subjects: Astronomy; Astrophysics and Astroparticles; Astrophysics and Cosmology; Celestial bodies; Corona; Coronagraphs; Curve fitting; Emission analysis; Emission lines; Height; Height variations; Magnetic fields; Maxima; Physics; Physics and Astronomy; Polar environments; Polar regions; Solar activity; Solar corona; Solar cycle; Solar magnetic field; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; solar corona; coronal line intensity; spectral coronal lines
• ISSN: 0010-9525; 1608-3075
• DOI: 10.1134/S0010952522700162

The results of studies of the coronal emission line λ = 5303 Å (Fe XIV) for the period of solar cycle 24 are presented. The spectral data were obtained with an out-of-eclipse Lyot coronagraph at the Mountain Astronomical Station of the Pulkovo Observatory, Russian Academy of Sciences (near Kislovodsk). As a result of processing of out-of-eclipse observations, a database of three types of daily coronal maps of green line intensity
I
5303
was created with a height distribution
h
from 1
R
☉
to 1.38
R
☉
(
R
☉
is the radius of the Sun). Irregularities along the λ = 5303 Å line were found and identified, which were associated with the configuration of magnetic fields in the solar corona above active regions. The length of the green line from the position angle of the Sun was calculated. We have shown that the time distribution of the line length in the polar regions has two maxima, which coincide with the times of the reversal of the polar magnetic field on the Sun. The maximum values of the average length of the coronal line along the entire limb occur in 2012–2014. For different phases (the rise, the period of maximum, the decline, and the minimum solar activity) of this solar cycle and for different regions of solar activity, dependences of the height variations of the
I
5303
values were plotted and studied. The regression equations for these fitting curves are presented. The variation in
I
5303
with height for the polar regions is most likely determined by a logarithmic function, and the approximating trend curves for the remaining latitudinal zones are determined by a third-order power function.