CfA Colloquium Schedule Spring 2010
 1 April 2010

1 April 2010

Speaker: Margaret Meixner (STScI / Visiting Scientist at CfA)

Title:The Life Cycle of Matter in the Magellanic Clouds: Insights from the Spitzer SAGE Surveys

Abstract:The life cycle of baryonic matter in a galaxy is driven by the exchange of material between the interstellar medium (ISM) and stars, which are the agents of galaxy evolution. Dust is present at these key transition phases of matter: in the ISM, in the circumstellar environments of newly forming stars and in stellar ejecta of dying stars. The Spitzer wavelengths provide a sensitive probe of circumstellar and interstellar dust and hence, allows us to study the physical processes of the ISM, the formation of new stars and the injection of mass by evolved stars and their relationships on a galaxy-wide scale. Due to their proximity, well constrained viewing angle, multi-wavelength information, and measured tidal interactions with the Milky Way (MW) and each other, the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are uniquely suited for surveying the agents of galaxy evolution (SAGE), the ISM and stars. In this talk, I will present an overview of the Spitzer SAGE survey results from SAGE-LMC, SAGE-SMC and SAGE-Spec with an overriding focus on the mass budget of the LMC. The SAGE-LMC survey, which has been completed, has revealed over 6 million sources including ~150,000 evolved stars, >2,000 young stellar objects and the diffuse ISM with column densities >1.2x10^{21} H/cm2. The diffuse infrared emission in the LMC can be associated with individual gas/dust clouds, thereby permitting unique studies of dust processes in the ISM. The SAGE team is working toward a complete census of newly formed stars with masses >1-3 Msun in order to understand whether tidally-triggered star formation events in the LMC are sustained or short-lived. The complete census of evolved stars with mass loss rates >1x10^{-8} Msun/yr will quantitatively measure the rate at which evolved stars inject mass into the ISM. I will end with a brief forward look to the Herschel HERITAGE survey of the Magellanic clouds and future prospects with the James Webb Space Telescope Mission.

Video of the Presentation (Talks can be viewed with RealPlayer. Free download is available from )


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