IRAS 22036+5306: an Al2O3 oxide-dominated post-AGB star |
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| Authors: | M M Maldoni † T R Ireland G Robinson |
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| Institution: | Research School of Earth Sciences, The Australian National University, Canberra ACT 0200, Australia;School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Australian Defence Force Academy, Canberra ACT 2600, Australia |
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| Abstract: | Radiative transfer modelling of the Infrared Space Observatory ( ISO ) spectrum of IRAS 22036+5306 has shown that its unusual 11-μm band can be suitably modelled with an alumina-olivine mixture substantially dominated by the former. The results of this work add further credence to recent findings that significant amounts of Al 2O3 dust grains are present in the dust shells of stars near or beyond the tip of the asymptotic giant branch. Indeed, in the case of IRAS 22036+5306, Al 2O3 dominates the dust composition to the extent that it shifts the 9.8-μm band due to amorphous silicates to 11 μm. IRAS 22036+5306 may be an unusual case in that the inner dust torus is maintained at a sufficiently high temperature for Al 2O3 condensation, but not silicate. |
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| Keywords: | radiative transfer stars: AGB and post-AGB circumstellar matter dust extinction infrared: stars |
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