Poster Presentation

The evolved-star dust budget of the Small Magellanic Cloud from model fits to multi-epoch, multi-band data

Sundar Srinivasan (ASIAA), Martha Boyer (NASA/GSFC), Margaret Meixner (STScI), Ciska Kemper (ASIAA), David Riebel (USNA), and Benjamin A. Sargent (RIT)

Asymptotic giant branch (AGB) and red supergiant (RSG) stars dissipate their mass into the ISM in the form of slow winds over ~10^(4-5) yr. These winds consist of gas molecules and dust particles which form in copious amounts in the cool, dense circumstellar environments around AGB/RSG stars. The dispersal of this material into the ISM drives the subsequent evolution of the galaxy by increasing its average metallicity and aiding in the formation of the next generation of stars.

In this study, we estimate the AGB/RSG dust budget to the Small Magellanic Cloud (SMC). We use three epochs of Spitzer data obtained by the SAGE-SMC (Surveying the Agents of Galaxy Evolution of the SMC; Gordon et al. 2011) and S3MC (Spitzer Survey of the SMC; Bolatto et al. 2005) to constrain the mid-infrared spectral energy distributions (SEDs) of our AGB/RSG candidates. We further incorporate optical and near-infrared variability information to generate multi-band SEDs. In order to estimate the luminosities and dust-production rate (DPR) from each star, we fit the observations with models from the Grid of RSG and AGB ModelS (GRAMS; Sargent et al. 2011, Srinivasan et al. 2011).

We find that our global dust budget estimate is consistent with previous determinations by Boyer et al. (2012) and Matsuura et al. (2013). The ratio of carbonaceous to silicate dust produced by AGB stars is slightly higher than in the Large Magellanic Cloud. Such a higher ratio is expected based on the lower metallicity of the SMC. However, the ratio is smaller for the SMC if RSGs are taken into account; this is because of the relatively larger number of RSGs compared to the LMC.