• Hora, Joseph
• Indebetouw, R.
• Meade, M.
• Blum, R. D.
• Whitney, B.
• Vijh, U.
• Markwick-Kemper, F.
• Misselt, K.
• Block, M.
• For, B.
• Engelbracht, C.
• Volk, Kevin
• Gordon, Karl
• Srinivasan, Sundar
• Meixner, Margaret
• Team, Sage
• Leitherer, C.
• Babler, B.

Abstract

The Spitzer photometric survey of the Large Magellanic Cloud (SAGE) has the sensitivity to detect all evolved stars of luminosity 1000 L ☉ or higher. In order to estimate the global mass return to the interstellar medium for these stars we will need to (a) classify the type of object based upon the available photometry from Spitzer, and 2MASS where available; and (b) estimate the dust shell properties directly from these observations. This will require calculating a grid of dust radiative transfer models to cover the range of parameters suitable for stars in the LMC and having an automatic algorithm for selecting the best fit model for each observed object. Given the lower metallicity of the LMC compared to the Galaxy we need to study some of the brighter objects in detail including fitting of spectroscopy observations to understand the basic dust properties for both oxygen-rich objects with silicate dust and carbon-rich objects with amorphous carbon and silicon-carbide dust. The dust to gas mass ratio must also be estimated, as it is expected to be somewhat higher than the values derived for galactic objects. We will show some preliminary results of the modelling work for a small number of the brighter AGB stars or M-type supergiants in the LMC, as well as discussing the identification of groups of objects in the multi-color space defined by the Spitzer IRAC, Spitzer MIPS, and 2MASS observations. The SAGE Project is supported by NASA/Spitzer grant 1275598 and NASA NAG5-12595.

Topics

• impedance spectroscopy
• amorphous
• Carbon
• Oxygen
• carbide
• Silicon