Physics & Astronomy ETDs

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Heights of formation are calculated for several of the solar spectral lines studied by the National Aeronautics and Space Administration - Goddard Space Flight Center (NASA-GSFC) New Mexico Solar Station at Sacramento Peak Observatory. These lines are Ca II H, K, 8498 Å and 8542 Å, MgI b1, NaI D1 and D2 and Sil 4103 Å. I calculate the heights of formation for each of these lines along with upper and lower confidence limits representing the height region where 90% of the total intensity of the line is formed in the solar photosphere and chromosphere. The necessary atmospheric and atomic data for each line were taken from recent papers using quiet-sun data without the assumptions of local thermal equilibrium (LTE). I assume a plane-parallel atmosphere and only compute outward directed intensities along an observer's line of sight. I compute the heights of formation at various wavelengths from line center by numerically integrating over all height, each specified atmospheric grid height (intervals of 50 or 100 km) multiplied by an appropriate weighting factor known as the contribution function, CΔλ. The contribution function is calculated by two different methods; the emission function which measures the contribution to the total line intensity at each height interval and the response function which weights each height interval according to the amount of change in its contribution to the line intensity due to small atmospheric perturbations at that height. I find in the resulting calcuations that both the emission and response functions, as well as the line intensities, for the SiI 4103 Å, NaI D and MgI b1 lines, are sensitive to changes in atmospheric parameters such as ne, Te and dξv/dh. The lines are formed throughout the chromosphere-photosphere region from 0-1800 km above the base of the photosphere, with the difference in calculated values of the heights of formation between the emission and response functions less than the estimated errors in my calculations of ±100 km. I present a discussion, through examples of several recent models and observations, of how the lines may be useful in probing the height structure of quiet and active solar features by observing line Dopper-shifting, core reversals, profile asymmetries and broadening which may be due to possible changes in the local atmospheric densities; temperature, material flows or microvelocity gradients. By using these results, I attempted to place the lines into a vertical height scheme so that it may be possible to sort, organize and perform preliminary interpretation of actual data.

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Level of Degree


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Physics & Astronomy

First Committee Member (Chair)

David Solomon King

Second Committee Member

Colston Chandler

Third Committee Member

Howard Carnes Bryant

Fourth Committee Member

Harrison P. Jones



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