First detection of methanol towards a post-AGB object, HD101584

H. Olofsson, W. H. T. Vlemmings, P. Bergman, E. M. L. Humphreys, M. Lindqvist. M. Maercker, L. Nyman, S. Ramstedt, D. Tafoya

Published 2017-06-26Version 1

The circumstellar environments of objects on the asymptotic giant branch and beyond are rich in molecular species. Nevertheless, methanol has never been detected in such an object, and is therefore often taken as a clear signpost for a young stellar object. However, we report the first detection of CH3OH in a post-AGB object, HD101584, using ALMA. Its emission, together with emissions from CO, SiO, SO, CS, and H2CO, comes from two extreme velocity spots on either side of the object where a high-velocity outflow appears to interact with the surrounding medium. We have derived molecular abundances, and propose that the detected molecular species are the effect of a post-shock chemistry where circumstellar grains play a role. We further provide evidence that HD101584 was a low-mass, M-type AGB star.