Bibcode
Imai, H.; Morris, M.; Sahai, R.; Hachisuka, K.; Azzollini F., J. R.
Bibliographical reference
Astronomy and Astrophysics, v.420, p.265-271 (2004)
Advertised on:
6
2004
Journal
Citations
27
Refereed citations
22
Description
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+2131 of
μl=-4.6±0.7 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.