  The IRAS source, 19312+1950, exhibits SiO maser emission, which is
predominantly detected in evolved stars enshrouded by a cold molecular
envelope. In fact, the mojority of the observational properties of IRAS
19312+1950 is consistent with the nature of an asymptotic giant branch (AGB)
star or post-AGB star. Interestingly, however, some of the observational
properties cannot be readily explained within the standard scheme of stellar
evolution, and those are rather reminiscent of young stellar objects. In the
present research we considered the evolutionary status of IRAS 19312+1950 as
revealed by the VLBI and MERLIN observations in SiO, H2O and OH maser lines.
The double-peaked profile of the 22 GHz H2O maser line is clearly detected,
with the emission regions of its red and blue-shifted components separately
located, leaving a space of about 10.9 mas between them. The kinematic
properties of H2O maser emission region appear to be more consistent with a
bipolar flow rather than other interpretations such as the Keplerian rotation
of a disk. The red-shifted component of the SiO maser emission, which exhibits
a double-peak profile in previous single-dish observations, is clearly detected
in the present interferometry, while the 1612 MHz OH maser line exhibits a
complicated line profile consisting of a single strong peak and many weak,
high-velocity spikes. The structure of OH maser emission region is partially
resolved, and the kinematic properties of the OH maser emission region are
reminiscent observations of a spherically expanding shell, even though the
evidence is scant. Collectively, the maser observations described here provide
additional support for the evolved star hypothesis for IRAS 19312+1950.
