The bipolar nebula IRAS 19312$+$1950 is a unique SiO maser source exhibiting both properties of young and evolved objects. To clarify the nature of this object, we made molecular line observations with the Nobeyama 45-m radio telescope. We detected emission from O-bearing ($\mathrm{HCO}^{{+}}\mkern-2.0mu$, SiO, SO, and $\mathrm{SO}_2$), C–and N-bearing molecules (CN, CS, HCN, HNC, $\mathrm{NH}_{3}$, $\mathrm{N}_{2}\mathrm{H}^{+}\mkern-2.0mu$, $\mathrm{HC}_{3}\mathrm{N}$, $\mathrm{H}_2\mathrm{CS}$, and $\mathrm{CH}_3\mathrm{OH}$), and their isotopic species (C${{17\atop} \mathrm{O}}, {{13\atop} \mathrm{C}}$${{18\atop} \mathrm{O}}$, and C${{34\atop} \mathrm{S}}$). The line profiles consist of weak broad ($\Delta v \sim 30 \,\mathrm{km} \,\mathrm{s}^{-1}$) and/or strong narrow ($\Delta v \lesssim 5 \,\mathrm{km} \,\mathrm{s}^{-1}$) components, depending on the molecular species. Strong time variations of $\mathrm{H}_2\mathrm{O}$ and SiO masers were also observed. Numerical modeling of the envelope with the LVG-code resulted in a good fit of the model with a mass loss rate of $2.6 \times10^{-4} \,{{{M}_{\odot}}} \,\mathrm{yr}^{-1}$ to the observed intensities for the broad-component lines. On the other hand, non-O-bearing molecules, which only have narrow profiles, were found to have abundances typical of those in cool dust clouds. No isotopic enrichment was found, indicating little evidence of the narrow cool component being ejecta of the central AGB star or a possible companion. These facts compelled us to conclude that IRAS 19312$+$1950 is an exotic mass-losing evolved star embedded in a low-mass ($\sim 20 \; \,{{{M}_{\odot}}}$) dark cloud.

We present the results of observations of cold IRAS sources in the Galactic disk area, −10 • < l < 100 • and |b| < 5 • , in the SiO J = 1-0, v = 1 and 2 maser lines. SiO masers were detected in 51 out of 143 observed sources; 45 were new detections in SiO masers. The selected IRAS sources were objects with dust temperatures of between 160 and 280 K. According to a confirmation using 2MASS near-infrared images, a majority of the sample are AGB or post-AGB stars, although dense cores in the starforming regions (or dusty Hii regions) are involved in part of the sample. Among new detections, two were candidates for post-AGB stars: IRAS 18450−0148 (W 43A), and 19312+1950. We found that the intensity ratios of the SiO J = 1-0, v = 2 to the v = 1 line of the objects clearly correlate with those IRAS colors. The detection rates of SiO masers tend to increase toward the Galactic center as well as the cases of previous SiO maser surveys of typical AGB stars. No strong associations of the objects to the spiral arms were found. The radial-velocity dispersion of the present sample is comparable with the dispersion of the SiO maser sample of typical AGB stars. These facts suggest that the present sample of cold IRAS sources with SiO masers has a kinematic property very similar with that of typical AGB stars.

We report Very Long Baseline Array and Very Large Array observations of 22 GHz H 2 O and 43 GHz SiO ( , ) maser emission as well as 7 mm continuum emission in W43A, which exhibits a highly v p 1 J p 1-0 collimated jet of molecular gas and a spherically expanding envelope very similar to that of an OH/IR star. The spatiokinematical structure of the H 2 O masers is well fitted to a precessing jet model with an expansion velocity of 150 km s Ϫ1 and a dynamical age of ∼50 yr. The spatiokinematical structure of the SiO masers is well fitted to a biconically expanding flow model, whose axis is parallel to the direction of the collimated jet. Astrometry of the H 2 O and SiO masers suggests that these maser sources have a common dynamical center, possibly as part of a binary system, within 70 AU. The SiO masers may be excited on the surface of the cone that has significant deceleration and interacts with the jet. A 7 mm continuum emission source is located ∼1300 AU away from these maser sources at a position angle of about Ϫ60Њ from the jet axis. The physical relation of the continuum to the maser sources is still unclear.

A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (H i) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder * Hubble Fellow. telescope. The survey will study the distribution of H i emission and absorption with unprecedented angular and velocity resolution, as well as molecular line thermal emission, absorption, and maser lines. The area to be covered includes the Galactic plane (|b| < 10°) at all declinations south of δ = +40 • , spanning longitudes 167 • through 360 • to 79 • at b = 0 • , plus the entire area of the Magellanic Stream and Clouds, a total of 13 020 deg 2 . The brightness temperature sensitivity will be very good, typically σ T 1 K at resolution 30 arcsec and 1 km s −1 . The survey has a wide spectrum of scientific goals, from studies of galaxy evolution to star formation, with particular contributions to understanding stellar wind kinematics, the thermal phases of the interstellar medium, the interaction between gas in the disk and halo, and the dynamical and thermal states of gas at various positions along the Magellanic Stream.

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We have surveyed ∼ 400 known large-amplitude variables within 15 ′ of the galactic center in the SiO J = 1-0 v = 1 and 2 maser lines at 43 GHz, resulting in 180 detections. SiO lines were also detected from 16 other sources, which are located within 20 ′′ (the telescope half beamwidth) of the program objects. The detection rate of 48 percent is comparable to that obtained in Bulge IRAS source surveys. Among the SiO detections, five stars have radial velocities greater than 200 km s −1 . The SiO detection rate increases steeply with the period of light variation, particularly for stars with P > 500 d, where it exceeds 80%. We found that, at a given period, the SiO detection rate is approximately three times that for OH. These facts suggest 1 that the large-amplitude variables in the Nuclear Disk region are AGB stars similar in their overall properties to the inner and outer Bulge IRAS/SiO sources. From the set of radial velocity data, the mass distribution within 30 pc of the galactic center is derived by a new method which is based on the collisionless Boltzmann equation integrated along the line of sight. The mass within 30 pc is about 6.4[±0.7] × 10 7 M ⊙ and the mass of the central black hole is 2.7[±1.3] × 10 6 M ⊙ . Consideration of the line-of-sight velocity of each star and its potential energy leads to the conclusion that the five high-velocity stars come from galactocentric distances as high as 300 pc. The high-velocity subsample of stars with negative radial velocities exhibits a tendency to have brighter K magnitudes than the subsample of stars with positive velocities. The origin of these high-velocity stars is discussed.

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