Mon. Not. R. Astron. Soc., 457, 2814-2838 (2016/April-2)
The evolved-star dust budget of the Small Magellanic Cloud: the critical role of a few key players.
SRINIVASAN S., BOYER M.L., KEMPER F., MEIXNER M., SARGENT B.A. and RIEBEL D.
Abstract (from CDS):
The life cycle of dust in the interstellar medium is heavily influenced by outflows from asymptotic giant branch (AGB) and red supergiant (RSG) stars, a large fraction of which is contributed by a few very dusty sources. We compute the dust input to the Small Magellanic Cloud (SMC) by fitting the multi-epoch mid-infrared spectral energy distributions of AGB/RSG candidates with models from the Grid of RSG and AGB ModelS grid, allowing us to estimate the luminosities and dust-production rates (DPRs) of the entire population. By removing contaminants, we guarantee a high-quality data set with reliable DPRs and a complete inventory of the dustiest sources. We find a global AGB/RSG dust-injection rate of (1.3±0.1) x 10–6 M☉/yr, in agreement with estimates derived from mid-infrared colours and excess fluxes. As in the Large Magellanic Cloud, a majority (66 per cent) of the dust arises from the extreme AGB stars, which comprise only ≃7 per cent of our sample. A handful of far-infrared sources, whose 24 µm fluxes exceed their 8 µm fluxes, dominate the dust input. Their inclusion boosts the global DPR by ≃1.5x, making it necessary to determine whether they are AGB stars. Model assumptions, rather than missing data, are the major sources of uncertainty; depending on the choice of dust shell expansion speed and dust optical constants, the global DPR can be up to ≃10 times higher. Our results suggest a non-stellar origin for the SMC dust, barring as yet undiscovered evolved stars with very high DPRs.
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
stars: AGB and post-AGB - stars: carbon - stars: mass-loss - supergiants - Magellanic Clouds
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<Available at CDS (J/MNRAS/457/2814): table5.dat>
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