We study a very young star-forming region in the outer Galaxy that is the most concentrated source of outflows in the Spitzer Space Telescope GLIMPSE360 survey. This region, dubbed CMa-l224, is located in the Canis Major OB1 association. CMa-l224 is relatively faint in the mid-infrared, but it shines brightly at the far-infrared wavelengths as revealed by the Herschel Space Observatory data from the Hi-GAL survey. Using the 3.6 and 4.5 µm data from the Spitzer/GLIMPSE360 survey, combined with the JHK s 2MASS and the 70-500 µm Herschel/Hi-GAL data, we develop a young stellar object (YSO) selection criteria based on color-color cuts and fitting of the YSO candidates' spectral energy distributions with YSO 2D radiative transfer models. We identify 293 YSO candidates and estimate physical parameters for 210 sources well-fit with YSO models. We select an additional 47 sources with GLIMPSE360only photometry as 'possible YSO candidates'. The vast majority of these sources are associated with high H 2 column density regions and are good targets for follow-up studies. The distribution of YSO candidates at different evolutionary stages with respect to Herschel filaments supports the idea that stars are formed in the filaments and become more dispersed with time. Both the supernova-induced and spontaneous star formation scenarios are plausible in the environmental context of CMa-l224. However, our results indicate that a spontaneous gravitational collapse of filaments is a more likely scenario. The methods developed for CMa-l224 can be used for larger regions in the Galactic plane where the same set of photometry is available.

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One of the major puzzles in the study of stellar evolution is the formation process of bipolar and multi-polar planetary nebulae. There is growing consensus that collimated jets create cavities with dense walls in the slowly-expanding (10-20 km s −1 ) envelope ejected in previous evolutionary phases, leading to the observed morphologies. However, the launching of the jet and the way it interacts with the circumstellar material to create such asymmetric morphologies have remained poorly known. Here we present for the first time CO emission from the asymptotic giant branch star W43A that traces the whole stream of a jet, from the vicinity of its driving stellar system out to the regions where it shapes the circumstellar envelope. We found that the jet has a launch velocity of 175 km s −1 and decelerates to a velocity of 130 km s −1 as it interacts with circumstellar material. The continuum emission reveals a bipolar shell with a compact bright dot in the centre that pinpoints the location of the driving source of the jet. The kinematical ages of the jet and the bipolar shell are equal, τ ∼60 years, indicating that they were created simultaneously, probably by a common underlying mechanism, and in an extremely short time. These results provide key initial conditions for the theoretical models that aim to explain the formation of bipolar morphologies in the circumstellar envelopes of low and intermediate mass stars.

We present the results of a 22 GHz H 2 O maser survey toward a new sample of AGB and post-AGB star candidates. Most of the objects are selected for the first time based on the AKARI data, which have high flux sensitivity in the mid-infrared ranges. We aim at finding H 2 O maser sources in the transient phase between the AGB and post-AGB stage of evolution, where the envelopes start to develop large deviations from spherical symmetry. The observations were carried out with the Effelsberg 100 m radio telescope. Among 204 observed objects, 63 detections (36 new) were obtained. We found 4 objects which may be "water fountain" sources (IRAS 15193+3132, IRAS 18056−1514, OH 16.3−3.0, and IRAS 18455+0448). They possess an H 2 O maser velocity coverage much smaller than those in other known water fountains. However, the coverage is still larger than that of the 1612 MHz OH maser. It implies that there is an outflow with a higher velocity than the envelope expansion velocity (typically ≤25 km s −1 ), meeting the criterion of the water fountain class. We suggest that these candidates are possibly oxygen-rich late AGB or early post-AGB stars in a stage of evolution immediately after the spherically symmetric AGB mass-loss has ceased.Subject headings: infrared: stars -masers -stars: AGB and post-AGB -stars: evolution -stars: winds, outflows 300 OH/IR stars, which are oxygen-rich late AGB stars with very thick envelopes, based on their IRAS [12]−[25] and [25]−[60] colors. They achieved a detection rate up to ∼50% using the Effelsberg 100 m radio telescope, and the results demonstrated the effectiveness of the color selection method. Another large-scale H 2 O maser survey was reported by Lewis (1997), but here the author focused on color-selected Mira variables instead of OH/IR stars, and 18 new detections were found from ∼200 objects. The Haystack 37 m radio telescope was used for this observation. A few more H 2 O maser surveys carried out before the year2000 are summarized in the Arcetri Catalog (Valdettaro et al. 2001, and references therein); -4all of the sources in the catalog were observed with the Medicina 32 m radio telescope. A recent notable survey of similar nature was conducted by Deacon et al. (2007). This time the target of interest shifted to the post-AGB stars. Their searched objects included 85 post-AGB stars selected by 1612 MHz OH maser properties and IRAS colors. The Tidbinbilla 70 m radio telescope was used for the maser observation, and 21 detections were obtained. The most important result from Deacon et al. (2007) was the discovery of 3 new "water fountain (WF)" sources. There were 9 more post-AGB H 2 O maser sources reported by Suárez et al. (2007) and Suárez et al. (2009), which also included 2 new WFs. WFs are mainly oxygen-rich late AGB or post-AGB stars exhibiting high velocity collimated bipolar outflows (or jets) traced by H 2 O maser emission (e.g., Imai et al. 2012). They are suggested to be transitional objects and their jets contribute to the shaping of planetary nebulae (PNe) (see, Imai 2007...