Skip to main content

Research Repository

Advanced Search

An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS). IV. Discovery of High-redshift AGB Analogs

Van Loon

An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS). IV. Discovery of High-redshift AGB Analogs Thumbnail


Authors



Abstract

The survey for DUST in Nearby Galaxies with Spitzer (DUSTiNGS) identified several candidate Asymptotic Giant Branch (AGB) stars in nearby dwarf galaxies and showed that dust can form even in very metal-poor systems (${\boldsymbol{Z}}\sim 0.008\,{Z}_{\odot }$). Here, we present a follow-up survey with WFC3/IR on the Hubble Space Telescope (HST), using filters that are capable of distinguishing carbon-rich (C-type) stars from oxygen-rich (M-type) stars: F127M, F139M, and F153M. We include six star-forming DUSTiNGS galaxies (NGC 147, IC 10, Pegasus dIrr, Sextans B, Sextans A, and Sag DIG), all more metal-poor than the Magellanic Clouds and spanning 1 dex in metallicity. We double the number of dusty AGB stars known in these galaxies and find that most are carbon rich. We also find 26 dusty M-type stars, mostly in IC 10. Given the large dust excess and tight spatial distribution of these M-type stars, they are most likely on the upper end of the AGB mass range (stars undergoing Hot Bottom Burning). Theoretical models do not predict significant dust production in metal-poor M-type stars, but we see evidence for dust excess around M-type stars even in the most metal-poor galaxies in our sample ($12+\mathrm{log}({\rm{O}}/{\rm{H}})=7.26\mbox{--}7.50$). The low metallicities and inferred high stellar masses (up to ~10 ${M}_{\odot }$) suggest that AGB stars can produce dust very early in the evolution of galaxies (~30 Myr after they form), and may contribute significantly to the dust reservoirs seen in high-redshift galaxies.

Citation

Van Loon. (2017). An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS). IV. Discovery of High-redshift AGB Analogs. Astrophysical Journal, https://doi.org/10.3847/1538-4357/aa9892

Acceptance Date Nov 4, 2017
Publication Date Dec 20, 2017
Journal Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
DOI https://doi.org/10.3847/1538-4357/aa9892
Keywords dwarf, stars, AGB and post-AGB, carbon, mass-loss, techniques, photometric
Publisher URL http://dx.doi.org/10.3847/1538-4357/aa9892

Files






You might also like



Downloadable Citations