IRAS 03201+5459: a C–rich AGB star with silicate absorption


IRAS 03201+5459 is a late–type star with a circumstellar envelope according to its IRAS color. It has no identification at optical or near–infrared wavelengths. A full ISO–SWS spectrum between 2.3 and 43 μm was taken at a resolution of about ∼300 to investigate its nature. The spectrum shows the 9.7 μm feature in absorption, usually seen in O–rich envelopes, and the 3 μm feature in absorption which is related to C–rich late–type stars. Furthermore, modeling of the spectral energy distribution indicates the necessity of C–based dust. To understand these conflicting spectral features, we have estimated interstellar extinction in the direction of IRAS 03201+5459 by different methods. In no case can we get a sufficiently large AV to explain the observed strength of the 9.7 μm absorption feature as due to interstellar extinction. Therefore, we investigated the hypothesis that a central C–rich star is surrounded by an inner C–rich shell and an outer O–rich shell (the object may be in the transition stage of evolution from an O–rich to a C–rich star). However, this require a very short lifetime of the object as a C–rich star, and then the similarity between IRAS and ISO spectra makes this hypothesis difficult to sustain. Alternatively O–rich material around the C–star IRAS 03201+5459 might be confined into more stationary disk–like configuration which is seen (almost) edge–on.

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@inproceedings{Jiang2000IRAS0A, title={IRAS 03201+5459: a C–rich AGB star with silicate absorption}, author={Bo Jiang and Shuji Deguchi}, year={2000} }