Asymptotic Giant Branch (AGB) stars are major contributors of cosmic dust to the universe. Typically, dust around AGB stars is investigated via radiative transfer (RT) modeling, or via simple deconstruction of observed spectra. However, methodologies applied vary. Using archival spectroscopic, photometric, and temporal data for the archetypal dusty star, Mira, we identify its circumstellar silicate dust grains. This is achieved by matching the positions and widths of observed spectral features with laboratory data. To do this comparison properly, it is necessary to account for the continuum emission. Here we investigate various ways in which a continuum is eliminated from observational spectra and how it affects the interpretation of spectral features. We find that while the precise continuum shapes and temperatures do not have a critical impact on the positions and shapes of dust spectral features, it is important to eliminate continua in a specific way. It is important to understand what contributes to the spectrum in order to remove the continuum in a way that allows comparison with laboratory spectra of candidate dust species. Our methodologies are applicable to optically thin systems, like that of Mira. Higher optical depths will require RT modeling, which cannot include many different potential astrominerals because there is a lack of complex refractive indices. Finally, we found that the classic silicate feature exhibited by Mira is not consistent with a real amorphous silicate alone but may be best explained with a small alumina contribution to match the observed FWHM of the ∼10μm feature.

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Stars between about 0.8 and 8 times the mass of the Sun will eventually evolve, becoming asymptotic giant branch (AGB) stars, where they pulsate and eject mass from their atmospheres, forming dust shells in the space around them. Evolved low- and intermediate-mass stars with carbon-to-oxygen ratios (C/O) below unity are known as oxygen-rich stars. O-rich stars are surrounded by dust shells containing mineral species dominated by silicate dust grains. In this dissertation, I examine whether dust grains around evolved, oxygen-rich AGB stars have any correlation with maser emission, and to understand the connection, if any, between specific types of maser emission and dust spectral features. I have investigated several methods of continuum elimination using spectroscopy data for the archetypal dusty AGB star, Mira. I have investigated the ~10[mu]m and ~18[mu]m spectral features in the continuum-eliminated spectrum including peak position, barycenter, and full width half maxima (FWHM). The positions and widthved spectral features were compared with those seen in laboratory spectra. I then looked for a correlation between maser emission and dust spectral features in a sample of Mira variables. The types of masers have been identified, and peak positions, barycenter positions, and FWHM have been measured for the sample spectra. The results show that the method of continuum elimination matters for correct identification of dust minerals, while varying the temperature and precise continuum shapes do not have a major effect on the positions of spectral features. Observed astronomical silicate features are complex and indicate the need for different compositions of minerals. Finally, there does not appear to be a correlation between the presence of a maser and dust spectral features based on the information available for analysis.