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

Context. Water maser emission at 22 GHz is a useful probe for studying the transition between the nearly spherical mass loss in the asymptotic giant branch (AGB) to a collimated one in the post-AGB phase. In their turn, collimated jets in the post-AGB phase could determine the shape of planetary nebulae once photoionization starts. Aims. We intend to find new cases of post-AGB stars and planetary nebulae (PNe) with water maser emission, including some especially interesting and rare types: water fountains (evolved objects with high velocity collimated jets traced by water masers) or water-maser-emitting PNe. Since previous studies have shown a higher detection rate of water maser emission in evolved objects that are optically obscured, we selected a sample that contains a significant fraction of post-AGB and young PN candidate sources showing signs of strong obscuration. Methods. We searched for water maser emission in 133 evolved objects using the radio telescopes in Robledo de Chavela, Parkes, and Green Bank. Results. We detected water maser emission in 15 sources of our sample, of which seven are reported here for the first time (IRAS 13483−5905, IRAS 14249−5310, IRAS 15408−5413, IRAS 17021−3109, IRAS 17348−2906, IRAS 17393−2727, and IRAS 18361−1203. We identified three water fountain candidates: IRAS 17291−2147, with a total velocity spread of 96 km s −1 in its water maser components and two sources (IRAS 17021−3109 and IRAS 17348−2906) that show water maser emission whose velocity lies outside the velocity range covered by OH masers. We have also identified IRAS 17393−2727 as a possible new watermaser-emitting PN. Conclusions. The detection rate is higher in obscured objects (14%) than in those with optical counterparts (7%), which is consistent with previous results. Water maser emission seems to be common in objects that are bipolar in the near-IR (43% detection rate in such sources). The water maser spectra of water fountain candidates like IRAS 17291−2147 show significantly fewer maser components than others (e.g., IRAS 18113−2503). We speculate that most post-AGBs may show water maser emission with wide enough velocity spread (≥100 km s −1 ) when observed with enough sensitivity and/or for long enough periods of time. Therefore, it may be necessary to single out a special group of "water fountains", probably defined by their high maser luminosities. We also suggest that the presence of both water and OH masers in a PN is a better tracer of its youth, than is the presence of just one of these species.

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“…The water maser emission traces a collimated jet (Imai et al 2004. Our spectrum shows five distinct components spanning a range of 115 km s −1 .…”

Section: Iras 19134+2131mentioning

confidence: 79%

A search for water maser emission toward obscured post-AGB star and planetary nebula candidates

Gómez

Rizzo

Suárez

et al. 2015

A&A

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“…As revealed by recent high-angular resolution observations, the spatial structure of the H 2 O masers in water-fountain sources is indeed peculiar: the masers are occur in collimated winds or jets, aligned with the symmetry axis of the nebulae (e.g. Imai et al 2004;Boboltz & Marvel 2005). These maser spots are located at distances that range between 870 AU and 600 AU from the central star, i.e.…”

Section: Resultsmentioning

confidence: 97%

Water vapor and silicon monoxide maser observations in the protoplanetary nebula OH 231.8+4.2

Desmurs

Alcolea

Contreras

et al. 2007

A&A

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Context. OH 231.8+4.2 is a well studied preplanetary nebula (pPN) around a binary stellar system that shows a remarkable bipolar outflow. Aims. To study the structure and kinematics of the inner 10-80 AU nebular regions probed by SiO and H 2 O maser emission, where the agents of wind collimation are expected to operate, in order to gain insights into the, yet poorly known, processes responsible for the shaping of bipolar pPNe. Methods. We performed high-resolution observations of the H 2 O 6 1,6 -5 2,3 and 28 SiO v = 2, J = 1-0 maser emissions with the Very Long Baseline Array. The absolute position of both emission distributions were recovered using the phase referencing technique, and accurately registered in HST optical images. Results. Maps of both masers were produced and compared. H 2 O maser clumps are found to be distributed in two areas of 20 mas in size spatially displaced by ∼60 milli-arcs along an axis oriented nearly north-south. SiO masers are tentatively found to be placed between the two H 2 O maser emitting regions, probably indicating the position of the Mira component of the system. Conclusions. The SiO maser emission traces an inner equatorial component with a diameter of 12 AU, probably a disk rotating around the M-type star. Outwards, we detect in the H 2 O data a pair of polar caps, separated by 80 AU. We believe that the inner regions of the nebula probably have been altered by the presence of the companion, leading to an equator-to-pole density contrast that may explain the lack of H 2 O masers and strong SiO maser emission in the denser, equatorial regions.

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“…There have been no detections of OH maser emission (Likkel et al 1992). The H 2 O maser emission also reveals bipolar jets, with a dynamical age of around 50 yr old, although these are less collimated than for W43A (Imai et al 2004). From measurements of the secular motion of the maser spots, a far kinematic distance of !16 kpc has been determined for this source ( Imai et al 2004).…”

Section: H 2 O Maser Variabilitymentioning

confidence: 94%

“…The origin of these jets is unclear, although in recent years there has been increasing evidence for high-velocity, short-lived jets from post-AGB stars. In some cases the jets are traced by OH or H 2 O maser emission or through radio continuum (e.g., Miranda et al 2001;Imai et al 2002Imai et al , 2004Boboltz & Marvel 2005).…”

Section: Introductionmentioning

confidence: 99%

H₂O Maser Observations of Candidate Post‐AGB Stars and Discovery of Three High‐Velocity Water Sources

Deacon

Chapman

Green

et al. 2007

ApJ

106

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We present the results of 22 GHz H 2 O maser observations of a sample of 85 postYasymptotic giant branch ( post-AGB) candidate stars, selected on the basis of their OH 1612 MHz maser and far-infrared properties. All sources were observed with the Tidbinbilla 70 m radio telescope, and 21 detections were made; 86 GHz SiO Mopra observations of a subset of the sample are also presented. Of the 21 H 2 O detections, 15 are from sources that are likely to be massive AGB stars and most of these show typical, regular H 2 O maser profiles. In contrast, nearly all the detections of more evolved stars exhibited high-velocity H 2 O maser emission. Of the five sources seen, v223 (W43A, IRAS 18450À0148) is a well-known ''water-fountain'' source that belongs to a small group of post-AGB stars with highly collimated, high-velocity H 2 O maser emission. A second source in our sample, v270 (IRAS 18596+0315), is also known to have high-velocity emission. We report the discovery of similar emission from a further three sources, d46 (IRAS 15445À5449), d62 (IRAS 15544À5332), and b292 (IRAS 18043À2116). The source d46 is an evolved post-AGB star with highly unusual maser properties. The H 2 O maser emission from d62 is probably associated with a massive star. The source b292 is a young post-AGB star that is highly likely to be a water-fountain source, with masers detected over a velocity range of 210 km s À1 .

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

Cited by 28 publications

References 11 publications

A search for water maser emission toward obscured post-AGB star and planetary nebula candidates

A search for water maser emission toward obscured post-AGB star and planetary nebula candidates

Water vapor and silicon monoxide maser observations in the protoplanetary nebula OH 231.8+4.2

H₂O Maser Observations of Candidate Post‐AGB Stars and Discovery of Three High‐Velocity Water Sources

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

Cited by 28 publications

References 11 publications

A search for water maser emission toward obscured post-AGB star and planetary nebula candidates

A search for water maser emission toward obscured post-AGB star and planetary nebula candidates

Water vapor and silicon monoxide maser observations in the protoplanetary nebula OH 231.8+4.2

H2O Maser Observations of Candidate Post‐AGB Stars and Discovery of Three High‐Velocity Water Sources

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H₂O Maser Observations of Candidate Post‐AGB Stars and Discovery of Three High‐Velocity Water Sources