I discuss circumstellar dust around evolved stars, focusing on the recently discovered crystalline silicates. I show that the stars surrounded by dust with a high abundance of crystalline silicates are all sources which are known or expected to have a disk. I apply simple model fits to the spectra and find that the amorphous silicates are warmer than the crystalline silicates, which I attribute to a difference in Fe-content. The low temperature of crystalline silicates requires long-wavelength spectroscopy to detect them. I also find that enstatite is more abundant than forsterite. I discuss the use of the width and wavelength of the 69 μm feature, which is attributed to forsterite, as a temperature indicator.
ISO Beyond the Peaks: The 2nd ISO Workshop on Analytical Spectroscopy
- Pub Date:
- November 2000
- DUST: CRYSTALLINE SILICATES