Spectroscopy of IRAS sources with far IR colors similar to those of planetary nebulae

Abstract

Optical candidates of 17 unidentified IRAS sources with far-infrared colors similar to planetary nebulae have been detected on sky survey plates. Low resolution CCD spectra of seven optical candidates suggests that they are post asymptotic giant branch (AGB) A-F-G supergiants. Their location in the Hertzsprung-Russell (HR) diagram and the presence of detached cold dust shells with far-infrared colors similar to planetary nebulae suggests that they are low mass stars and have been experienced severe mass loss in the recent past during their AGB stage of evolution.