The Dust and Flux Contribution from AGB Stars in the Local Group

When low- to intermediate-mass stars (0.8 < M < 8 M_sun) begin to ascend the asymptotic giant branch (AGB), pulsations levitate material from the stellar surface and provide density enhancements and shocks, encouraging dust formation and re-processing. This dust is subsequently released to the interstellar medium via a strong stellar wind driven mainly by radiation pressure on the grains. This dusty stellar wind causes AGB stars to radiate strongly in the near- to mid-infrared, potentially affecting measurements of star-formation histories of distant galaxies at these wavelengths.  I will discuss recent observations of AGB stars in nearby galaxies and clusters, including estimates of the AGB dust return and infrared flux contribution in a wide range of environments.  Particularly, I will focus on the Spitzer surveys of the Small and Large Magellanic Clouds.

http://www.stsci.edu/~mboyer/