scholarly journals Water and OH Maser Emission from the Planetary Nebula K3-35

2003 ◽  
Vol 209 ◽  
pp. 263-266 ◽  
Author(s):  
Yolanda Gómez ◽  
Luis F. Miranda ◽  
Guillem Anglada ◽  
JosÉ M. Torrelles
Keyword(s):  
Planetary Nebula ◽  
Central Star ◽  
Minor Axis ◽  
Water Molecules ◽  
Giant Star ◽  
Maser Emission ◽  
Giant Stars ◽  
Water Masers ◽  
Unambiguous Detection ◽  
Water Maser

Water-vapour masers, typical of the envelopes in giant stars, are not expected to persist in planetary nebulae due to the ultraviolet radiation of the remnant star that progressively destroys the molecules. Recently, we have reported the first unambiguous detection of water maser emission in a planetary nebula, K 3–35 (Miranda et al. 2001). The water masers in K3–35 were detected at the center of the nebula, along the minor axis, at a radius of ~85 AU and also at the surprisingly large distance of 5000 AU from the star, at the tips of the bipolar lobes. The existence of these water molecules is puzzling, and probably we are observing the very moment of transformation of a giant star into a planetary nebula. Miranda et al. (2001) also report the presence of polarization in the OH 1665 MHz masers, which are distributed towards the central star in a torus-like structure. Here we review the main results on this source.

scholarly journals Maser emission in planetary nebulae

2007 ◽  
Vol 3 (S242) ◽  
pp. 292-298 ◽  
Author(s):  
Yolanda Gómez
Keyword(s):  
Water Vapor ◽  
Mass Loss ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Central Star ◽  
Asymptotic Giant Branch ◽  
Kinematic Modeling ◽  
Maser Emission ◽  
The Core ◽  
Unambiguous Detection

AbstractStars at the top of the asymptotic giant branch (AGB) can exhibit maser emission from molecules like SiO, H2O and OH. These masers appear in general stratified in the envelope, with the SiO masers close to the central star and the OH masers farther out in the envelope. As the star evolves to the planetary nebula (PN) phase, mass-loss stops and ionization of the envelope begins, making the masers disappear progressively. The OH masers in PNe can be present in the envelope for periods of ~1000 years but the H2O masers can survive only hundreds of years. Then, H2O maser emission is not expected in PNe and its detection suggests that these objects are in a very particular moment of its evolution in the transition from AGB to PNe. We discuss the unambiguous detection of H2O maser emission in two planetary nebulae: K 3-35 and IRAS 17347-3139. The water-vapor masers in these PNe are tracing disk-like structures around the core and in the case of K3-35 the masers were also found at the tip of its bipolar lobes. Kinematic modeling of the H2O masers in both PNe suggest the existence of a rotating and expanding disk. Both PNe exhibit a bipolar morphology and in the particular case of K 3-35 the OH masers are highly polarized close to the core in a disk-like structure. All these observational results are consistent with the models where rotation and magnetic fields have been proposed to explain the asymmetries observed in planetary nebulae.

scholarly journals Imaging the water masers toward the H2O-PN IRAS 18061–2505

2012 ◽  
Vol 8 (S287) ◽  
pp. 258-259
Author(s):  
Yolanda Gómez ◽  
Daniel Tafoya ◽  
Olga Suárez ◽  
Jose F. Gómez ◽  
Luis F. Miranda ◽  
...  
Keyword(s):  
Planetary Nebulae ◽  
Central Star ◽  
Large Array ◽  
Maser Emission ◽  
Very Large Array ◽  
Kinematical Model ◽  
Water Masers ◽  
Central Stars ◽  
Water Maser

AbstractIt has been suggested that the presence of disks or tori around the central stars of pre Planetary Nebulae and Planetary Nebulae is related to the collimation of the jet that are frequently observed in these sources. These disks or tori can be traced by the maser emission of some molecules such as water. In this work we present Very Large Array (VLA) observations of the water maser emission at 22 GHz toward the PN IRAS 18061–2505, for which the masers appear located on one side of the central star. For comparison with the observations, we present a simple kinematical model of a disk rotating and expanding around the central star. The model matches qualitatively the observations. However, since the masers appear only on one side of the disk, these results are not conclusive.

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

2015 ◽  
Vol 578 ◽  
pp. A119 ◽  
Author(s):  
J. F. Gómez ◽  
J. R. Rizzo ◽  
O. Suárez ◽  
A. Palau ◽  
L. F. Miranda ◽  
...  
Keyword(s):  
Planetary Nebula ◽  
Maser Emission ◽  
Water Maser

scholarly journals Probing Accretion Disks in AGN with Water Masers

1997 ◽  
Vol 163 ◽  
pp. 113-125
Author(s):  
Philip R. Maloney
Keyword(s):  
Accretion Disk ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Quantitative Information ◽  
X Rays ◽  
Maser Emission ◽  
Radiative Efficiency ◽  
Physical Conditions ◽  
Water Masers ◽  
Water Maser

AbstractExtremely luminous extragalactic water masers – the so-called “megamasers”, with isotropic luminosities of tens to hundreds of solar luminosities – appear to be uniquely associated with active galactic nuclei. The recent survey of Braatz et al. indicates that 20% of Seyfert 2 galaxies have detectable water maser emission. Although originally suggested to arise in shocks, it now seems likely that the masers arise from the irradiation of high-pressure molecular gas by X-rays from the AGN. Quantitative modelling shows that the observed megamaser luminosities can plausibly be produced in this fashion. Both observational limits on the size scales and the high gas pressures required indicate that the water maser emission arises on very small scales, either in a circumnuclear “torus” or the accretion disk itself. In the best-studied case, NCG 4258, the masers are produced in a geometrically thin, warped accretion disk. The maser models can be used to derive quantitative information about the physical conditions in the disk, namely, the mass accretion rate, and therefore the radiative efficiency. I discuss the implications of water maser observations and models for the study of accretion disks and circumnuclear tori in AGN.

scholarly journals A Collimated Molecular Jet in W 43A Traced by Water Maser Emission

2003 ◽  
Vol 209 ◽  
pp. 267-268
Author(s):  
Hiroshi Imai ◽  
Tetsuo Sasao ◽  
Kumiko Obara ◽  
Toshihiro Omodaka ◽  
Philip J. Diamond
Keyword(s):  
Planetary Nebula ◽  
Stellar Object ◽  
The Other ◽  
Maser Emission ◽  
Other Hand ◽  
Systemic Velocity ◽  
Short Period ◽  
The Common ◽  
Water Maser

We present VLBA observations of the spatial and velocity distributions of 22 GHz H2O and 1612 MHz OH masers in the OH/IR star W 43A. These masers have the same systemic velocity and are, therefore, likely to be associated with the common stellar object. However, the kinematical structures of them are quite different and independent. Most of the H2O masers are extremely collimated spatially and kinematically. The H2O maser jet also seems to be precessing. On the other hand, the OH masers exhibit clear arc-shaped structures indicating a spherically-expanding shell with weak collimation. The W 43A jet is very likely to be predominantly composed of hot molecules traced by H2O maser emission and formed in the immediate vicinity of an unknown star next to another OH/IR star. Such a “molecular jet” is likely to appear only during the short period before a star forms an elongated planetary nebula.

scholarly journals Monitoring of extragalactic water masers with the MPIfR 100-m telescope

2002 ◽  
Vol 206 ◽  
pp. 392-395
Author(s):  
Yoshiaki Hagiwara ◽  
Christian Henkel ◽  
William A. Sherwood
Keyword(s):  
Radio Telescope ◽  
Radio Galaxy ◽  
Maser Emission ◽  
Monitoring Period ◽  
Water Masers ◽  
Water Maser

We present single-dish monitoring of the 22 GHz water maser lines from the Seyfert 2 galaxies NGC 3079, M51(NGC 5194), NGC 5793, and the radio galaxy NGC 315 with the Effelsberg 100-m radio telescope. During the monitoring period of 1995 − 2001, the H2O masers flared in M51 and NGC 5793, while maser emission from NGC 315 was not detected in 1996 and 2000. During 2000, we discovered new red-shifted velocity features in NGC 3079 and blue-shifted features in M51. These velocity components are crucial to model the distribution of maser emission in each galaxy.

scholarly journals A collimated molecular jet in W 43A traced by water maser emission

2002 ◽  
Vol 206 ◽  
pp. 80-83
Author(s):  
Hiroshi Imai ◽  
Tetsuo Sasao ◽  
Kumiko Obara ◽  
Toshihiro Omodaka ◽  
Philip J. Diamond
Keyword(s):  
Stellar Evolution ◽  
Position Angle ◽  
Proper Motions ◽  
Maser Emission ◽  
Water Masers ◽  
Water Maser

We present the spatial and velocity distributions of water masers in W 43A. Most of the maser features are spatially and kinematically collimated to a surprising extent. It is very likely that the jet in W 43A is predominantly composed of warm molecules traced by water maser emission. The position angle of the spatial collimation of the maser clusters is slightly different from the directions of both the cluster separation and the proper motions. We propose a model involving a precessing jet to explain the axis offsets. The discovery of a molecular jet with precession in W 43A provides important information on our understanding of the formation of collimated molecular jets and may provide clues on specific stages of stellar evolution.

scholarly journals CO in the Bipolar Nebula NGC 2346

1989 ◽  
Vol 131 ◽  
pp. 205-205
Author(s):  
A. P. Healy ◽  
P. J. Huggins
Keyword(s):  
Planetary Nebula ◽  
Molecular Form ◽  
Central Star ◽  
Minor Axis ◽  
Molecular Gas ◽  
Astronomy Observatory ◽  
Star System ◽  
Mapping Data ◽  
North West ◽  
Rectangular Distribution

We report on observations of the J = 2-1 line of CO to study the distribution and kinematics of the molecular gas in the bipolar planetary nebula NGC 2346. The data were obtained with the National Radio Astronomy Observatory 12-m telescope whose beamsize (FWHM = 30″) partially resolves the CO emitting region. A map of the velocity integrated emission shows a roughly rectangular distribution, approximately 53″ × 34″, oriented along the minor axis of the optical nebula. The CO spectrum towards the central star system is strongly double peaked. The mapping data show that this results from two distinct regions which are offset south-east and north-west of the center with radial velocities which are, respectively, larger and smaller than that of the star system. Overall the CO data are consistent with an expanding and partially disrupted distribution of molecular gas around the waist of the optical nebula. Mass estimates confirm that a substantial amount of the matter ejected by the star system is still in molecular form.

Water-maser emission from a planetary nebula with a magnetized torus

Nature ◽  
2001 ◽  
Vol 414 (6861) ◽  
pp. 284-286 ◽  
Author(s):  
L. F. Miranda ◽  
Y. Gómez ◽  
G. Anglada ◽  
J. M. Torrelles
Keyword(s):  
Planetary Nebula ◽  
Maser Emission ◽  
Water Maser

scholarly journals Powerful Water Masers in Active Galactic Nuclei

2002 ◽  
Vol 19 (4) ◽  
pp. 401-421 ◽  
Author(s):  
Philip R. Maloney
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Rotating Disk ◽  
Future Prospects ◽  
Maser Emission ◽  
X Ray ◽  
Central Engine ◽  
Water Masers ◽  
Water Maser

AbstractLuminous water maser emission in the 616–523 line at 22GHz has been detected from two dozen galaxies. In all cases the emission is confined to the nucleus and has been found only in AGN, in particular, in Type 2 Seyferts and LINERs. I argue that most of the observed megamaser sources are powered by X-ray irradiation of dense gas by the central engine. After briefly reviewing the physics of these X-Ray Dissociation Regions, I discuss in detail the observations of the maser disk in NGC 4258, its implications, and compare alternative models for the maser emission. I then discuss the observations of the other sources that have been imaged with VLBI to date, and how they do or do not fit into the framework of a thin, rotating disk, as in NGC 4258. Finally, I briefly discuss future prospects, especially the possibility of detecting other water maser transitions.

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