H₂O and SiO maser emission in Galactic center OH/IR stars ^*,**

¹ Onsala Space Observatory, 439 92 Onsala, Sweden
² Joint Institute for VLBI in Europe, Radiosterrenwacht, PO Box 2, 7990 AA Dwingeloo, The Netherlands
³ N.R.A.O. Array Operations Center, PO Box 0, Socorro, NM 87801, USA
⁴ MERLIN/VLBI National Facility, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL, UK

Corresponding author: L. O. Sjouwerman (Socorro), lsjouwerm@nrao.edu

Received: 15 July 1999
Accepted: 6 March 2002

Abstract

We have performed targeted surveys for 22 GHz H₂O and 43 GHz SiO maser emission in Galactic center OH/IR stars using the Very Large Array. Some of the detections have been used in a previous paper to investigate the possibility of measuring milli-arcsecond accurate positions (to obtain stellar proper motions) in the Galactic center. Here we report on the detection of at least 25 H₂O masers and 18 SiO masers associated with stars within 2° and 15´ of Sgr A*, respectively. This survey has more than doubled the total number of proper motion candidates to at least about 50 stellar objects. The stellar SiO masers are best suited for proper motion studies, although the initial OH, H₂O or SiO maser positions may not be well enough determined to use for a-priori VLBI positions. Serendipitously we also found 8 H₂O masers in the molecular cloud M-0.13-0.08.