The following document lists the file abstract/RIVISON_AGBDUST.abs
from catalogue VI/111.
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Maser surveys have shown that many potential OH/IR stars have no OH masers in their CS envelopes, despite modest requirements which should be implicitly met by IRAS colour-selected candidates. It is probable that these `OH/IR colour mimics' are related to symbiotic stars and have a degenerate companion (hidden in the optical and near-IR by circumstellar dust) which disrupts the masing action. Here we propose to compare far-IR line emission from colour mimics with that from symbiotic stars. The circumstellar dust shells will be much less opaque in the far-IR and, since a hot companion would inevitably stimulate line emission, our spectra will constitute a simple and effective test of whether hot stars are present. Line intensities and ratios for symbiotics (and mimics, if lines are detected) will be used to analyse abundances and ionization conditions. The temperature of any colour mimic companions will help to tie down the mechanism (be it radiative or gravitational) by which masers are suppressed in symbiotic Miras. Our sample contains examples of colour mimics with a range of IRAS colours and LRS types, as well as symbiotics with AGB giants and first-ascent giants. These have been chosen to avoid duplication of the symbiotic and OH/IR stars in the Core Programme.