I am a rising senior at the University of Wyoming. I am majoring in Physics and Astrophysics with minors in Creative Writing and Honors. I am participating in this Solar REU program this summer in order to learn if Grad school is for me and, if so, what I can specialize in.
My project is a continuation of the project done during the Solar Physics REU 2021. The goal is to use data collected from the Hinode XRT solar satellite in order to derive the Solar Irradiance constant in X-rays in the units Watts per meter squared, and to observe how this constant changes over time. The Sun's activity increases and decreases in an 11-year cycle, and the Solar Irrandiance constant fluctuates as well along this same cycle. Total Solar Irradiance, especially light in the visible spectrum, only fluctuates about 0.1% during this cycle. X-ray irradiance, on the other hand, fluctuates on the order of thousands.
To accomplish the task for this REU project, I will need to analyze satellite data of the Sun using Thin-Be and Al-Mesh filters, by first calculating the electron count in each image. Next, I will use the intensities found and the Filter Ratio Method to calculate the Sun's temperature and emission measure. Finally, using the Chianti database, I will calculate the irradiance of the Sun in the Soft X-ray spectrum over the course of the mission.
The above presentations include my biweekly progress reports. All citations for the information used within these presentations are included on the last slide.
The purpose of this REU project is to study how the Sun’s irradiance in the soft x-ray spectrum changes over time. To do this, we used image data from Hinode/XRT using Al-mesh and thin-Be filters from January 2008 to April 2022. Using this data, we calculated the Sun’s intensity in each image, its temperature, emission measure, and irradiance in soft x-rays. The calculations were performed using Chianti version 9 coronal abundances and Chianti version 10 coronal, hybrid, and photospheric abundances. Comparing Chianti 9 and 10 coronal abundance results reveals very little difference between the two, perhaps irradiance using Chianti 10 is a fraction greater than using Chianti 9. Comparing the different abundances used in Chianti 10 also show very little difference between their calculated irradiance. For both results, there is greater cohesion during periods of higher Solar activity. During periods of lower Solar activity, irradiance using Chianti 10 coronal abundances are higher compared to Chianti 9, and among Chianti 10 abundances, photospheric abundances have the highest irradiance while coronal abundances have the lowest.
During this REU, an additional study was begun to investigate how much irradiance is lost when calculating within 1.1 Solar radii. Four images of the Sun off-center with Al-mesh and thin-Be were used, however only one image was deemed fully accurate. This image was taken in July 2022 using longer exposure times, and accurate stray light patterns were recorded at the same time. Of the three remaining images, two remained uncorrected, and one was corrected using an approximated stray light pattern. The area of the Sun for which irradiance was being calculated was restrained so only 25% of the Sun is being used. The irradiance was shown to approach a limit as the radius was increased. This limit was approximated and then divided from the irradiance at 1.1 Solar radii in order to calculate the percentage of irradiance lost. According to the most accurate image used, about 8.799% of the Sun’s total irradiance is lost by limiting the calculations to 1.1 Solar radii.
Email: sboland@uwyo.edu
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