Physical Properties of 29 March 2006 Solar Corona

TL;DR

This study analyzes the 29 March 2006 solar eclipse to extract white-light corona properties (intensity, polarization, electron density, and temperature) using an 8-inch telescope and film-based calibration. It introduces an intensity calibration function based on solar-disk calibration images ($I_N$, $I_R$, and an exponential fit) and derives Stokes parameters from multi-exposure polarization data to compute $K+F$ brightness and polarization. By separating $K$ and $F$ components and applying a novel density-calibration approach, the authors obtain electron densities and mid-height temperatures that largely agree with minimum corona models ($VDH1950$, $SK1970$), with polarization remaining the main discrepancy likely due to instrumental limitations and solar-cycle asymmetry. The work validates the modeling framework during solar minimum and presents new methods for coronal density calibration, advocating future tests across additional eclipses to strengthen cycle-dependent coronal representations.

Abstract

On 29 March 2006, a total solar eclipse was observed in the Manavgat district of Antalya, Turkey. During the event, the solar corona was observed using an 8-inch mirrored telescope. White-light polarization observations were carried out at three distinct angles using a polarizing filter placed in front of the camera system. To calibrate the intensity of the roll film, photographs of the eclipse and the solar disk were taken with a traditional 35mm manual camera. Using the solar disk images obtained during the eclipse, an intensity calibration curve for the roll film was created. This curve was then used to calculate various physical properties of the solar corona, including intensity, degree of polarization, electron density, and mean temperature. The results of these calculations were compared with the corona models developed by \cite{VDH1950} and \cite{SK1970}, as well as with findings from other researchers. Except for the degree of polarization, the measured physical parameters closely match the values given in the literature.

Figures (12)

• Figure 1: The upper panel illustrates the position of the total eclipse cone of 29 March 2000 over the southern part of Turkey. The location of the observation site is indicated by a small red point and a circle. This site is situated in close proximity to the central line of the eclipse. Furthermore, the location of the observation site at Ilıca City Stadium is denoted by a small red location icon, as illustrated in the bottom-right image.
• Figure 2: Here is an example of the solar disk images taken for intensity calibration at the 1/4 second exposure with 5 different diaphragm openings. In the last two images, most of the solar disk has been moved outside the frame to prevent excessive saturation of the sky background
• Figure 3: All the images of the eclipse that were utilized in the calculation process. The sequence of numbers from left to right on the bottom of the image corresponds to the exposure time, the time of observation, and the polarization angle, respectively.
• Figure 4: The intensity calibration curve acquired for the 2006 eclipse. Each exposure time is shown using a different symbol. The solid line represents the curve fitted.
• Figure 5: (a) Isophotes of total coronal brightness (numbers are in the unit of 10$^{-9} I_{\odot}$) and (b) isolines of polarization degree (numbers are in percent) of the solar eclipse March 29, 2006.