The Infrared Spectrograph on the Spitzer Space Telescope observed over 200 carbon stars in nearby metal-poor dwarf galaxies. These spectra probe how the quantity and composition of dust produced by carbon stars depend on initial metallicity, initial mass, and pulsational properties. For stars to produce significant quantities of dust, they must be pulsating in the fundamental mode with strong amplitudes. The spectra confirm that carbon stars with longer pulsation periods produce more dust and that the amount of dust shows no strong dependence on metallicity. This sample includes more carbon stars with low mass and reveals that for a given pulsation period, higher-mass stars produce less dust. Evidence is building for the layering of dust grains, with SiC cores in grains produced by metal-rich carbon stars, and mantles of MgS around grains in all embedded stars.
American Astronomical Society Meeting Abstracts #225
- Pub Date:
- January 2015