EDP Sciences
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Volume 391, Number 3, September I 2002
Page(s) 967 - 978
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20020983

A&A 391, 967-978 (2002)
DOI: 10.1051/0004-6361:20020983

H $\mathsf{_2}$O and SiO maser emission in Galactic center OH/IR stars

L. O. Sjouwerman1, 2, 3, M. Lindqvist1, H. J. van Langevelde2 and P. J. Diamond3, 4

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

(Received 15 July 1999 / Accepted 6 March 2002)

We have performed targeted surveys for 22 GHz H 2O 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 H 2O 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, H 2O or SiO maser positions may not be well enough determined to use for a-priori VLBI positions. Serendipitously we also found 8 H 2O masers in the molecular cloud M-0.13-0.08.

Key words: masers -- surveys -- astrometry -- stars: AGB and post-AGB -- galaxy: center

Offprint request: L. O. Sjouwerman (Socorro), lsjouwerm@nrao.edu

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