Spitzer Sage/lmc Observations Of Extreme Carbon Stars As A Probe Of Carbon-rich Stardust Properties
Abstract
Intermediate mass stars eventually evolve into asymptotic giant branch (AGB) stars and are major contributors of new mateiral to the interstellar medium (ISM) and the next generation of stars. The Spitzer legacy program Surveying the Agents of Galaxy Evolution (SAGE) performed an infrared survey of the Large and Small Magellanic Clouds(LMC and SMC, respectively). SAGE's goal is to follow the life cycle of matter that drives galactic evolution. SAGE-Spec is the spectroscopic follow up project in which we study the dust production in more detail. Here we present a study of extreme carbon stars in the LMC. These stars have intermediate mass and are losing copious amounts of material to the ISM. These carbon stars have such high mass-loss rates that the dust shells they form completely obscure their starlight. The SAGE program has discovered that these extreme carbon stars are more common than expected compared to the number found in our own galaxy and for the sub-solar metallicity of the LMC. This dataset allows us to investigate the variations in properties of the dust around are fairly homogeneous sample of stars. We show that the emissivity of the dust around extreme carbon stars varies markedly and is rarely consistent with the commonly-assumed emissivity power-law value of 1.2.
- Publication:
-
American Astronomical Society Meeting Abstracts #219
- Pub Date:
- January 2012
- Bibcode:
- 2012AAS...21934302P