Bibcode
Imai, H.; Morris, M.; Sahai, R.; Hachisuka, K.; Azzollini F., J. R.
Referencia bibliográfica
Astronomy and Astrophysics, v.420, p.265-271 (2004)
Fecha de publicación:
6
2004
Revista
Número de citas
27
Número de citas referidas
22
Descripción
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.