Dust Production in Metal-Poor Local Group Galaxies Dust Production in Metal-Poor Local Group Galaxies

Observations with the Infrared Spectrograph on the Spitzer Space Telescope reveal several dependencies of mass loss and dust production in evolved stars on metallicity. As the metallicity decreases, the fraction of naked stars increases, and the SiO absorp-tion in the naked stars grows weaker. Among the oxygen-rich stars with circumstellar dust, the amount of dust decreases as metallicity decreases. The amount of dust pro-duced by carbon stars, on the other hand, does not appear to depend on metallicity. As metallicity decreases, a larger fraction of stars on the asymptotic giant branch become carbon rich, which means that metal-poor galaxies should have more carbon-rich dust and less oxygen-rich dust injected into the interstellar medium. Subject headings: dust, extinction — circumstellar matter — infrared: stars — stars: carbon 1