IRAS observations of OH/IR stars

Abstract

Preliminary results of IRAS survey observations of a sample of 40 very evolved stars, all detected originally as OH maser emission sources, are presented. In several cases, the spectrum is very much redder than for those sources identified from the ground. Color-color plots show that there is a continuous sequence from classical Mira variables to the reddest OH/IR stars. However, the reddest stars differ somewhat: they pulsate only weakly or not at all. Probably, they have reached the end of their evolution on the asymptotic giant branch.