OH/IR stars without OH masers - Nondetection statistics

Lewis, B. M.; Eder, J.; Terzian, Yervant

doi:10.1086/114536

Cited by 17 publications

(13 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: 84%

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: 84%

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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“…The others were found in SIMBAD. The references concerning the OH observations correspond to: (1) this paper; (2) Le Squeren et al (1992); (3) te Lintel Hekkert et al (1991); (4) Sivagnanam et al (1990); (5) Lewis et al (1990); (6) Galt et al (1989); (7) te Lintel ; (8) Eder et al (1988); (9) Lewis et al (1987); (10) …”

Section: A Summary Tablesmentioning

confidence: 98%

Infrared giants vs. supergiants

Josselin

Loup

Omont

et al. 1998

Astron. Astrophys. Suppl. Ser.

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Abstract. We report systematic observations of millimeter CO emission from a sample of 109 oxygen-rich evolved stars (AGB and supergiants), colour-selected from the IRAS Point Source Catalog (0.69 < S 25 µm /S 12 µm < 1.20). CO(1−0) has been searched with good sensitivity in 81 sources (74% of the sample). CO(1−0) is detected in 54 sources and a significant upper limit has been achieved in 27 sources.In our previous paper we reported on the statistical results of these observations. We showed that in almost 50% of the sources, the ratio of the IRAS 60 µm flux to CO intensity, R = S 60 /T mb (1−0), is larger by a factor of 3 to more than 10 than what is expected according to the correlation found by Nyman et al. (1992). Supergiants only exhibit very high values ( > ∼ 200). In most cases, the observed spread in the values of this ratio can be explained by a large range of luminosities. This leads to a new criterion to identify AGB stars: an object with R < 150 must have a low mass progenitor.Here we study the correlations between R and various physical properties of the sources. Most sources with high values of R also have low galactic latitudes, small IRAS variability indices, and early spectral types (typically M1-M5). Conversely, there is no dependence on the IRAS colours, nor on the intensity of silicate 10 µm emission. However, a few AGB stars exhibit large R; other factors than luminosity are required to explain these values. Different hypotheses, such as the possible presence of a chromosphere, a low 12 C abundance or a variable massloss rate, are examined. Considering the global high OH detection rate (∼ 67%), we studied the correlations with CO and OH emission. The detection of OH seems to be a useful discriminator of mechanisms that enhance R.

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“…It could well be that the Hipparcos data have been confused by the asymmetric surface brightness typical of late-type stars (Ragland et al 2006), especially so for a star as extended as L 2 Pup having a (predicted) apparent angular radius of 9.6 mas (Dumm & Schild 1998). A further argument against the binary nature of L 2 Pup is the detection of all three masers SiO, H 2 O and OH (Jura et al 2002), since a binary companion, when orbiting in the layers where the maser activity should originate, prevents its operation (Herman & Habing 1985;Lewis et al 1987;Schwarz et al 1995).…”

Section: Appendix: Dismissing the Binary Nature Of L2 Pupmentioning

confidence: 99%

Spectroscopic binaries among Hipparcos M giants

Jorissen¹,

Frankowski²,

Famaey³

et al. 2009

A&A

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Context. This paper is the third one in a series devoted to studying the properties of binaries involving M giants. Aims. We use a new set of orbits to construct the first (e − log P) diagram of an extensive sample of M giant binaries, to obtain their mass-function distribution, and to derive evolutionary constraints for this class of binaries and related systems. Methods. The orbital properties of binaries involving M giants were analysed and compared with those of related families of binaries (K giants, post-AGB stars, barium stars, Tc-poor S stars). Results. The orbital elements of post-AGB stars and M giants are not very different, which may indicate that, for the considered sample of post-AGB binaries, the post-AGB star left the AGB at quite an early stage (M4 or so). Neither are the orbital elements of post-mass-transfer binaries like barium stars very different from those of M giants, suggesting that the mass transfer did not alter the orbital elements much, contrary to current belief. Finally, we show that binary systems with e < 0.4 log P − 1 (with periods expressed in days) are predominantly post-mass-transfer systems, because (i) the vast majority of barium and S systems match this condition; and (ii) these systems have companion masses peaking around 0.6 M , as expected for white dwarfs. The latter property has been shown to hold as well for open-cluster binaries involving K giants, for which a lower bound on the companion mass may easily be set.

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OH/IR stars without OH masers - Nondetection statistics

Cited by 17 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

Infrared giants vs. supergiants

Spectroscopic binaries among Hipparcos M giants

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