How carbon stars die: The link between pulsations and dust production

Carbon stars dominate the measured dust production in nearby metal-poor galaxies.  The details of how they die will strongly influence both the dust ecosystem and the chemical evolution of galaxies in their quiescent phases.  Recent spectroscopic observations with SOFIA, along with photometry from Spitzer and WISE, reveal a close link between the pulsational behavior of carbon stars and the quantity and nature of the dust they produce.  If carbon stars are forming significant quantities of carbon-rich dust, then that dust is amorphous carbon, and they are pulsating as Miras, that is with both strong amplitudes and in the fundamental mode.  This clue points us to the key moment in the evolution of star, when it enters that final phase of high mass loss and dust production that will strip its core bare and reveal a white dwarf within a planetary nebula.