Volume 420, Number 1, June II 2004
|Page(s)||265 - 271|
|Section||Stellar structure and evolution|
|Published online||14 May 2004|
The kinematics of water masers in the stellar molecular outflow source, IRAS 19134+2131
Joint Institute for VLBI in Europe, Postbus 2, 7990 AA Dwingeloo, The Netherlands e-mail: firstname.lastname@example.org
2 Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1562, USA e-mail: email@example.com
3 Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA e-mail: Raghvendra.Sahai@jpl.nasa.gov
4 Departamento de Astronomía, Universitat de Valéncia, 46100 Burjassot, Spain e-mail: firstname.lastname@example.org
5 Instituto de Astrofísica de Canarias, La Laguna, Tenerife 38200, Spain e-mail: email@example.com
Corresponding author: H. Imai, firstname.lastname@example.org
Accepted: 4 March 2004
Using the Very Large Array (VLA) and the Very Long Baseline Array (VLBA), we have observed water maser emission in the proto-planetary nebula candidate IRAS 19134+2131, in which the water maser spectrum has two groups of emission features separated in radial velocity by ~100 km s-1. The blue-shifted and red-shifted clusters of maser features are clearly separated spatially by ~150 mas, indicative of a fast collimated flow. However, not all of the maser features are aligned along the axis of the flow, as is seen in the similar high-velocity water maser source, W43A. Comparing the VLA and VLBA maps of the water maser source, we find 4 maser features that were active for 2 years. Using only VLBA data, we identified proper motions for 8 maser features. The full 3D outflow velocity is estimated to be ~130 km s-1, indicating that the dynamical age of the flow is only ~50 yr. On the basis of the relative positions with respect to the nearby extragalactic reference source, J1925+2106, we also obtain a secular motion of IRAS 19134+2131of mas yr-1 along the Galactic plane toward the Galactic centre. This indicates a “far distance" (≥16 kpc) for IRAS 19134+2131 if the Galactic rotation curve remains flat at 220 km s-1.
Key words: masers / stars: AGB and post-AGB / stars: distances / stars: kinematics / stars: winds, outflows / stars: individual: IRAS 19134+2131
© ESO, 2004
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