The effect of aluminum on silicate spectral features
Abstract
Many astrophysical environments exhibit a spectral feature around 10 microns, which has long been attributed to amorphous silicates. However, the precise composition of almost ubiquitous silicate dust grains remains a mystery. Here we investigate the effect of aluminum on this common spectral feature. Aluminum (Al) is the fourth most abundant metal after Si, Mg, and Fe and is important in the nucleation of dust grains around stars. Furthermore aluminum is found in meteoritic presolar dust grains. Therefore, it is essential to expand our knowledge of how Al affects silicate spectral features. We examine the role of Al in silicate glasses by producing a range of compositions with known physical structure (polymerization or non-bridging oxygens to SiO4 tetrahedra; NBO/T). We have produced a set of 20 glass samples for which we have measured the precise composition and the glass transition temperature. We have calculated the value of NBO/T from the composition and taken mid-infrared spectra of each sample composition. We have measured the spectral parameters: peak position, barycenter, and FWHM of each ~10 micron spectral feature. We then sought trends between the various measured, modeled and calculated parameters. We show that there is a trend between Al content, NBO/T and the peak position of the spectra. Potential applications of these new spectra and their trends are also discussed.
- Publication:
-
American Astronomical Society Meeting Abstracts #223
- Pub Date:
- January 2014
- Bibcode:
- 2014AAS...22335107W