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| Paper: |
Metallicity Dependence of Oxygen-rich Dust around Evolved Stars |
| Volume: |
497, Why Galaxies Care about AGB Stars III: A Closer Look in Space and Time |
| Page: |
379 |
| Authors: |
Jones, O. C.; Kemper, F.; Srinivasan, S.; McDonald, I. |
| Abstract: |
Observations of evolved stars in Local Group galaxies show that
metallicity has a significant influence on the production and
chemical composition of dust. In order to determine the composition
of the dust in the circumstellar envelopes of oxygen-rich AGB stars,
we have computed a grid of MODUST radiative-transfer models
for a range of dust compositions, mass-loss rates, dust-shell inner
radii and stellar parameters. We use these models to fit a sample
of 37 O-rich AGB stars in the LMC with optically thin circumstellar
envelopes, for which 5–35 μm Spitzer infrared spectrograph
spectra and broad-band photometry from the optical to the mid-infrared
are available. From the modelling, we find mass-loss rates in the range
∼ 8×10–8 to 5×10–6 M☉ yr–1,
and we show that a grain mixture consisting primarily of amorphous
silicates, with contributions from amorphous alumina and metallic iron,
provides a good fit to the observed spectra. We relate these recent
results to other works at varying metallicity. |
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