The kinematics of water masers in the stellar molecular outflow source, IRAS 19134+2131

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
Número de autores
5
Número de autores del IAC
1
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.