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 Submillimeter Array observations of 321 GHz water maser emission in Cepheus A

2007 ◽  
Vol 3 (S242) ◽  
pp. 489-493
Author(s):  
Nimesh A. Patel ◽  
Salvador Curiel ◽  
Qizhou Zhang ◽  
T. K. Sridharan ◽  
Paul T. P. Ho ◽  
...  
Keyword(s):  
High Mass ◽  
Mass Star ◽  
Large Array ◽  
Maser Emission ◽  
Very Large Array ◽  
Star Forming ◽  
Water Masers ◽  
Cepheus A ◽  
First Time ◽  
Water Maser

AbstractUsing the Submillimeter Array (SMA) we have imaged for the first time the 321.226 GHz, 1029 − 936 ortho-H2O maser emission. This is also the first detection of this line in the Cepheus A high-mass star-forming region. The 22.235 GHz, 616 – 523 water masers were also observed with the Very Large Array 43 days following the SMA observations. Three of the nine detected submillimeter maser spots are associated with the centimeter masers spatially as well as kinematically, while there are 36 22 GHz maser spots without corresponding submillimeter masers. In the HW2 source, both the 321 GHz and 22 GHz masers occur within the region of ~1″ which includes the disk-jet system, but the position angles of the roughly linear structures traced by the masers indicate that the 321 GHz masers are along the jet while the 22 GHz masers are perpendicular to it. We interpret the submillimeter masers in Cepheus A to be tracing significantly hotter regions (600~2000 K) than the centimeter masers.

scholarly journals Water Fountains in Pre-Planetary Nebulae: The Case of IRAS16342–3814

2012 ◽  
Vol 8 (S287) ◽  
pp. 225-229 ◽  
Author(s):  
Mark Claussen ◽  
Raghvendra Sahai ◽  
Mark Morris ◽  
Hannah Rogers
Keyword(s):  
General Structure ◽  
Planetary Nebulae ◽  
Large Array ◽  
Very Large Array ◽  
Long Baseline ◽  
Stellar Velocity ◽  
Water Masers ◽  
Very Long Baseline Array ◽  
Water Maser

AbstractWe present a brief review of Very Long Baseline Array (VLBA) observations of water masers in the so-called water fountain pre-planetary nebulae, and report on new VLBA and Very Large Array (VLA) data for the water masers in the prototypical water fountain source IRAS16342–3814, taken approximately monthly in 2008–2009. A new and very strong water maser is found at an LSR velocity of −3 km s−1, which is offset from the central (likely stellar) velocity. The new VLBA observations still show a similar general structure as was observed in 2002, but there are details which are difficult to explain.

scholarly journals EVLA imaging of the water masers in the massive protostellar cluster NGC6334I

2012 ◽  
Vol 8 (S287) ◽  
pp. 502-503
Author(s):  
Todd R. Hunter ◽  
Crystal L. Brogan
Keyword(s):  
Spectral Resolution ◽  
Large Scale ◽  
High Spectral Resolution ◽  
Large Array ◽  
Maser Emission ◽  
Very Large Array ◽  
Broad Bandwidth ◽  
Molecular Lines ◽  
Water Masers ◽  
Spatial Kinematics

AbstractWe have used the recently-upgraded Karl G. Jansky Very Large Array (VLA) in A-configuration to observe the water masers in the massive protostellar cluster NGC6334I with broad bandwidth and high spectral resolution. Four groups of maser spots are found. The two groups with the broadest velocity span (40 km/s) are towards the UCHII region and the hot core SMA1. The spatial kinematics of the SMA1 masers are consistent in sense and orientation with the large-scale CO outflow and appear to trace the base of the outflow from a protostar at the dust peak of SMA1. Additional masers at the southern end of SMA1 provide evidence for a second protostar. The highest intensity maser lies about 2″ north of SMA1. Interestingly, no water masers are seen on the equally impressive hot core SMA2. Finally, we have detected maser emission toward the enigmatic source SMA4, which shows no millimeter molecular lines despite having strong, compact submillimeter continuum and may trace another protostar.

scholarly journals VLA observations of water maser emission associated with SVS 13

2002 ◽  
Vol 206 ◽  
pp. 59-62
Author(s):  
Luis F. Rodríguez ◽  
Guillem Anglada ◽  
José M. Torrelles ◽  
J. Eduardo Mendoza-Torres ◽  
Aubrey D. Haschick ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Radio Source ◽  
Angular Resolution ◽  
Radio Continuum ◽  
Large Array ◽  
Maser Emission ◽  
Very Large Array ◽  
Water Maser ◽  
East West ◽  
Made In

The young stellar object SVS 13 has been proposed as the powering source of the HH 7-11 objects. Recent observations have revealed that in the radio continuum (3.6-cm) the source is a binary separated by about 0.3 in the east-west direction. We present Very Large Array observations, made in the highest angular resolution A configuration, of H2O maser emission toward this source. Our data show that the H2O spots appear to be segregated in two velocity groups: a group with radial velocity similar to that of the ambient cloud (VLSR ⋍ 8 km s−1) that is associated with the western radio source, and a blueshifted (by ∼20 km s−1) velocity group that is associated with the eastern radio source. We discuss the possible implications of this observation.

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 Planetary Nebula Evolution Traced by Distance-Independent Parameters

1993 ◽  
Vol 155 ◽  
pp. 480-480
Author(s):  
C.Y. Zhang ◽  
S. Kwok
Keyword(s):  
Physical Properties ◽  
Mass Distribution ◽  
Planetary Nebula ◽  
Strong Support ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolution Model ◽  
The Core ◽  
Independent Parameters ◽  
Central Stars

Making use of the results from recent infrared and radio surveys of planetary nebulae, we have selected 431 nebulae to form a sample where a number of distance-independent parameters (e.g., Tb, Td, I60μm and IRE) can be constructed. In addition, we also made use of other distance-independent parameters ne and T∗ where recent measurements are available. We have investigated the relationships among these parameters in the context of a coupled evolution model of the nebula and the central star. We find that most of the observed data in fact lie within the area covered by the model tracks, therefore lending strong support to the correctness of the model. Most interestingly, we find that the evolutionary tracks for nebulae with central stars of different core masses can be separated in a Tb-T∗ plane. This implies that the core masses and ages of the central stars can be determined completely independent of distance assumptions. The core masses and ages have been obtained for 302 central stars with previously determined central-star temperatures. We find that the mass distribution of the central stars strongly peaks at 0.6 M⊙, with 66% of the sample having masses <0.64 MM⊙. The luminosities of the central stars are then derived from their positions in the HR diagram according to their core masses and central star temperatures. If this method of mass (and luminosity) determination turns out to be accurate, we can bypass the extremely unreliable estimates for distances, and will be able to derive other physical properties of planetary nebulae.

scholarly journals Class I methanol masers in the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 147-149
Author(s):  
L. O. Sjouwerman ◽  
Y. M. Pihlström
Keyword(s):  
Galactic Center ◽  
Class I ◽  
Large Array ◽  
Maser Emission ◽  
Very Large Array ◽  
Sagittarius A ◽  
Current Location ◽  
Theoretical Predictions ◽  
Methanol Masers ◽  
Sgr A

AbstractWe report on the detection of 36 and 44 GHz Class I methanol (CH3OH) maser emission in the Sagittarius A (Sgr A) complex with the Karl G. Jansky Very Large Array (VLA). These VLA observations show that the Sgr A complex harbors at least three different maser tracers of shocked regions in the radio regime. The 44 GHz masers correlate with the positions and velocities of previously detected 36 GHz CH3OH masers, but less with 1720 MHz OH masers. Our detections agree with theoretical predictions that the densities and temperatures conducive for 1720 MHz OH masers may also produce 36 and 44 GHz CH3OH maser emission. However, many 44 GHz masers do not overlap with 36 GHz methanol masers, suggesting that 44 GHz masers also arise in regions too hot and too dense for 36 GHz masers to form. This agrees with the non-detection of 1720 MHz OH masers in the same area, which are thought to be excited under even cooler and less dense conditions. We speculate that the geometry of the 36 GHz masers outlines the current location of a shock front.

Water masers as signposts of extremely young planetary nebulae

2017 ◽  
Vol 13 (S336) ◽  
pp. 377-380
Author(s):  
José F. Gómez ◽  
Luis F. Miranda ◽  
Lucero Uscanga ◽  
Olga Suárez
Keyword(s):  
Planetary Nebulae ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Water Masers ◽  
Water Maser

AbstractOnly five planetary nebulae (PNe) have been confirmed to emit water masers. They seem to be very young PNe. The water emission in these objects preferentially traces circumstellar toroids, although in K 3-35 and IRAS 15103-5754, it may also trace collimated jets. We present water maser observations of these two sources at different epochs. The water maser distribution changes on timescales of months to a few years. We speculate that these changes may be due to the variation of the underlying radio continuum emission, which is amplified by the maser process in the foreground material.

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