OH and H2O observations of cold IRAS stars

Likkel, L.

doi:10.1086/167804

Cited by 96 publications

(113 citation statements)

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“…This is a confirmed water fountain, and the only one in which OH emission has not been detected, despite several searches (Lewis et al 1987;Hu et al 1994;Likkel 1989).…”

Section: Iras 19134+2131mentioning

confidence: 86%

“…This object is a known water fountain, which was first detected by Likkel (1989), who obtained a water maser spectrum with a wide velocity range of ≥70 km s −1 , well outside the velocity range covered by the OH maser emission. The distribution and proper motions of the H 2 O maser emission (Day et al 2010) confirms that it arises from a collimated jet.…”

Section: Iras 19190+1102mentioning

confidence: 89%

“…The distribution and proper motions of the H 2 O maser emission (Day et al 2010) confirms that it arises from a collimated jet. The departure of the OH spectrum from the typical double-peaked profile in OH/IR stars (Likkel 1989) suggests that this object is already in the post-AGB phase. Our water maser spectrum shows components spanning ∼143 km s −1 .…”

Section: Iras 19190+1102mentioning

confidence: 94%

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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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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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“…This is a confirmed water fountain, and the only one in which OH emission has not been detected, despite several searches (Lewis et al 1987;Hu et al 1994;Likkel 1989).…”

Section: Iras 19134+2131mentioning

confidence: 86%

Section: Iras 19190+1102mentioning

confidence: 89%

Section: Iras 19190+1102mentioning

confidence: 94%

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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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“…Herman & Habing (1985) monitored OH17.7−2.0 at 1612 MHz over a period of 4 years from 1978 and detected only small flux-density variations. The shape and intensity of the 1612 MHz profile appear to be very stable over the last three decades (Bowers 1978;Likkel 1989;Bains et al 2003). IRAS measurements indicated that OH17.7−2.0 is non-variable; the percentage likelihood of variability, estimated from the 12 and 25 µm flux densities obtained generally at 2 week and 6 month intervals, is 21.…”

Section: Introductionmentioning

confidence: 91%

Burst of strongly polarized maser emission at 1612 MHz in the proto-planetary nebula OH17.7–2.0

Szymczak¹,

Gérard²

2005

A&A

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Abstract.We report the discovery of a burst of highly polarized OH maser emission at 1612 MHz in the proto-planetary nebula candidate OH17.7−2.0. The total flux density of two red-shifted features at 72.8 and 73.3 km s −1 increased nearly threefold over a period of ∼430 days. This burst was not associated with any systematic changes of the other 1612 MHz maser features as well as of the 1665 and 1667 MHz masers. The burst was characterized by a linear growth of left-hand circularly polarized emission accompanied by considerable linearly polarized emission. During the burst, the degrees of circular and linear polarization increased up to −80% and 15% respectively. A relation found between the line width and the peak flux density of the two bursting features implies a saturated amplification. Among several possible causes of the burst, a local propagation effect due to Zeeman overlap initiated by evolutionary changes in the shell appears most plausible.

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“…It is assumed that the visible semi-regular and Mira variables with relatively thin envelopes evolve towards OH/IR objects with thick envelopes, and when their pulsations cease, they leave the tip of the asymptotic giant branch and become post-AGB objects and eventually young planetary nebulae (Habing 1996, for review). Alternatively, OH/IR stars have higher progenitor masses than Miras (Likkel 1989) and may come from an intrinsically more massive population (Whitelock et al 1994). These categories of objects differ in pulsational and mass-loss properties and can be accompanied by OH maser emission.…”

Section: The Samplementioning

confidence: 99%

Polarization properties of OH masers in AGB and post-AGB stars

Wolak

Szymczak

Gérard

2011

A&A

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Context. Ground-state OH maser emission from late-type stars is usually polarized and remains a powerful probe of the magnetic field structure in the outer regions of circumstellar envelopes if observed with high angular and spectral resolutions. Observations in all four Stokes parameters are quite sparse and this is the most thorough, systematic study published to date. Aims. We aim to determine polarization properties of OH masers in an extensive sample of stars that show copious mass loss and search for candidate objects that are well-suited for high angular resolution studies. Methods. Full-polarization observations of the OH 1612 and 1667 MHz maser transitions were carried out for a sample of 117 AGB and post-AGB stars. Several targets were also observed in the 1665 MHz line. Results. A complete set of full-polarization spectra together with the basic polarization parameters are presented. Polarized features occur in more than 75% of the sources in the complete sample and there is no intrinsic difference in the occurrence of polarized emission between the three classes of objects of different infrared characteristics. The highest fractional polarization occurs for the post-AGB+PN and the Mira+SR classes at 1612 and 1667 MHz, respectively. Differences in the fractional polarization between the sources at different evolutionary stages appear to be related to depolarization caused by blending. The alignment of the polarization angles at the extreme sides of the shell implies a regular structure of the magnetic field of a strength of 0.3-2.3 mG. Conclusions. Polarized OH maser features are widespread in AGB and post-AGB stars. The relationship between the circular and linear fractional polarizations for a representative sample are consistent with the standard models of polarization for the Zeeman splitting higher than the Doppler line width, whereas the polarized features are the σ components.

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OH and H2O observations of cold IRAS stars

Cited by 96 publications

References 0 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

Burst of strongly polarized maser emission at 1612 MHz in the proto-planetary nebula OH17.7–2.0

Polarization properties of OH masers in AGB and post-AGB stars

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