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IRAS 19134+2131 (IRAS 1913+215P09)
-- a water
fountain star
 | Maser searches to 33 cold IRAS sources uncovered
11 OH masers and 6 H2O
masers. H2O masers in IRAS 19134+2131 (their H2O 54.9+4.6) were found to show a velocity spread of
111 km/s, larger than normal OH/IR stars. Vlsr = -66.1 km/s. OH masers were not found in IRAS 19134+2131. (from Engels et al., 1984A&A...140L...9E)
(fig: H2O maser spectrum.)
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| Monitoring of 1.3cm H2O maser spectra of 3 water fountain stars IRAS 16342-3814, IRAS 19134+2131 and
W 43A revealed variations as short as one
month. No maser feature velocity shift was found to be > 1km/s. The varying spectral features seemed to be
stable at several discontinuous fixed velocities for at least a few
years. The apparent symmetry in the H2O spectra allows determination of
the central velocities and suggests bipolar geometry. H2O maser velocity spreads are
dV = 130, 132, 180 km/s (disagree to the spectral
plots!?) and central velocities are Vlsr = +43.2+-0.9, -67.4+-0.4
and +33.6+-1.0 km/s for the 3 stars respectively.
(from Likkel et al.,1992A&A...256..581L)
(figure: left 2 col -- variation of
red half of H2O masers; right 2 col -- variation of blue half of H2O masers.)
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| VLA and VLBA observations of
H2O masers revealed bipolar jets in IRAS 19134+2131. The maser spots were crowded in two regions, with l.o.s. velocity separation
dV = ~100 km/s, angular separation of ~ 150 mas. With the help of proper motion measurement with VLBA, the radial jet velocity was found to be
~130 km/s and the dynamical age of the jets is
~50 yr (assuming a far distance of 16 kpc). Vlsr = -67 km/s. A motion of -4.6+-0.7 mas/yr
(towards the GC) was found. (from Imai et al., 2004A&A...420..265I)
(figure: left -- VLA map of H2O
maser spots; right -- VLBA map of H2O maser spots.)
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| HST images of all 23 well-resolved PPNs (another 5 unresolved) are reported. Wide variaties of non-spherical morphologies of these
PPNs are similar to that of young PNs. Prominent halos are found around central aspherical shapes in many objects, which represent
intact AGB CSEs. No round PPN is found, which demonstrates that the aspherical morphology of PNe has appeared before PN stage, instead of
being created by wind interaction. A new PPN morphology classification system
is suggested. The 23 PPNs and another 32 previously studied and resolved PPNs are classified. The maps of
IRAS 19134+2131 showed a partially resolved bipolar shape along the direction of H2O maser jets. The length in both F606W and F814W maps are 0.2"~0.3", roughly equals to the separation of the bipolar H2O jets (0.15").
No significant halo was detected. (from Sahai et al.,
2007AJ....134.2200S)
(figure: HST maps of IRAS 19134+2131.
The short line is the P.A. and length of the bipolar H2O maser jets.)
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| VLBA and HST image of IRAS 19134+2131 revealed highly collimated H2O maser jets and
optical bipolar reflection nebula. The dynamical age is
only ~40 yr. The optical lobes show similar size and good match with maser jets, indicating
the optical lobes are recently produced by the jets. Proper motion measurement within one year gives parallax
distance of 8.0+0.9-0.7 kpc. The 3D position of the star
in the Galaxy coordinate is (R,theta,z) = (7.4+0.4-0.3kpc, 62+-5deg, 0.65+0.07-0.06kpc), the 3D secular velocity is
(Vr,Vtheta,Vz) = (3+53-46, 125+20-28, 8+48-39) km/s.
(from Imai et al., 2007ApJ...669..424I)
(figure: left -- proper motion
velocities of maser spots; right -- a) proper motion in space, b)&c) proper motion against time, d)
relative proper motion.)
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