Circumstellar CO in OH/IR stars close to the Galactic Centre

Abstract

A pilot project is carried out to measure circumstellar CO emission from three OH/IR, stars close to the GC using the Nobeyama Millimeter Array at 115 GHz and the Sub-Millimeter Array at 230 GHz. An interferometer is necessary as a 'spatial filter' in this region of space because of the confusion with interstellar CO emission. The intention is to find out whether it is possible to later conduct a large-scale survey for mass-loss rates using, for example, ALMA. Thus an important parameter would be added to our understanding of the evolution of the Galactic Bulge. Sources have been detected towards two of the stars with correct positions and radial velocities. However, for one of the stars the line profile is not what one expects for expanding circumstellar envelopes. This surprising result is discussed and our plans for future observations are presented. © 2006 IOP Publishing Ltd.