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An OH survey for Post-Asymptotic Giant Branch stars

P. te Lintel Hekkert, J.M. Chapman

Abstract

We present a survey for OH maser emission at 18 cm in the direction of 196 IRAS point sources. The aim of the survey was to identify post-asymptotic giant branch stars. OH emission and/or absorption was detected in the direction of 77 sources of which 61 OH detections were previously unknown, giving an overall detection rate of 39 per cent. Fourteen maser sources associated with evolved stars or \pn\ were found. These included three \pn\ (two new OH detections), nine \ppn\ (three new OH detections) and two cold OH/IR stars (both previously known). Two sources were of uncertain identification (both new OH detections). The remainder of the OH sources were identified with known young stellar objects and \hii\ regions. The survey included the detection of OH maser emission from HD 101584, an early-type supergiant at high Galactic latitude. For several of the Post-Asymptotic Giant Branch (Post-AGB) stars changes have occurred in the OH spectral profiles over a period of several years. This is interpreted as evidence for rapid changes in the stellar wind, due either to an interaction with a stellar companion, nova-like events or rapid stellar evolution.

Keywords

Masers -- OH/IR stars -- (Post-) Asymptotic Giant Branch -- Planetary Nebulae