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| Paper: |
Exploring Mass-Loss in M-type AGB Stars |
| Volume: |
497, Why Galaxies Care about AGB Stars III: A Closer Look in Space and Time |
| Page: |
345 |
| Authors: |
Bladh, S.; Höfner, S.; Aringer, B.; Eriksson, K. |
| Abstract: |
Stellar winds observed in asymptotic giant branch (AGB) stars are
usually attributed to a combination of stellar pulsations and radiation
pressure on dust. Strong candidates for wind-driving dust species in
M-type AGB stars are magnesium silicates (Mg2SiO4 and MgSiO3).
Such grains can form close to the stellar surface; they consist of
abundant materials and, if they grow to sizes comparable to the
wavelength of the stellar flux maximum, they experience strong
acceleration by photon scattering. Here we present results from an
extensive set of time-dependent wind models for M-type AGB stars with
a detailed description for the growth of Mg2SiO4 grains.
We show that these models reproduce observed mass-loss rates and wind
velocities, as well as visual and near-IR photometry. However, the
current models do not show the characteristic silicate features at
10 and 18 μm, due to a rapidly falling temperature of
Mg2SiO4 grains in the wind. Including a small amount of Fe in
the grains further out in the circumstellar envelope will increase
the grain temperature and result in pronounced silicate features,
without significantly affecting the photometry in the visual and
near-IR. |
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