scholarly journals Time variations of water masers

2002 ◽  
Vol 206 ◽  
pp. 43-50 ◽  
Author(s):  
Tarja Liljeström ◽  
Carl R. Gwinn
Keyword(s):  
Magnetic Field ◽  
Flux Density ◽  
Line Width ◽  
Time Variation ◽  
Maser Line ◽  
Vlbi Data ◽  
Time Variations ◽  
Water Masers ◽  
Excellent Tool ◽  
Water Maser

The strong water maser line at 22 GHz is an excellent tool for studying shocked and turbulent interstellar regions, especially, if simultaneous single-dish and VLBI data are available. After a brief review of 22 GHz time variation studies, we focus on effects caused by magnetic field pressure on observed properties of water masers. We use the powerful and rich maser cluster W49N as an example. Furthermore, we point out the connection between postshock wave damping and observed excess in single-dish flux density and line width.

scholarly journals Water maser and radio continuum emission towards IRAS 23139+5939

2007 ◽  
Vol 3 (S242) ◽  
pp. 180-181
Author(s):  
M. A. Trinidad ◽  
S. Curiel ◽  
J. M. Torrelles ◽  
L. F. Rodríguez ◽  
V. Migenes ◽  
...  
Keyword(s):  
Flux Density ◽  
Line Emission ◽  
The Other ◽  
Radio Continuum ◽  
High Mass ◽  
Continuum Emission ◽  
Maser Line ◽  
Water Masers ◽  
Water Maser ◽  
The Continuum

AbstractWe present simultaneous observations of continuum (3.5 and 1.3cm) and water maser line emission (1.3cm) carried out with the VLA-A toward the high-mass object IRAS 23139+5939. We detected two radio continuum sources at 3.5cm separated by 0”5 (~2400 AU), I23139 and I23139S. Based on the observed continuum flux density and the spectral index, we suggest that I23139 is a thermal radio jet associated with a high-mass YSO. On the other hand, based on the spatio-kinematical distribution of the water masers, together with the continuum emission information, we speculate that I23139S is also a jet source powering some of the masers detected in the region.

scholarly journals Flaring water masers associated with W49N

2019 ◽  
Vol 628 ◽  
pp. A89 ◽  
Author(s):  
L. N. Volvach ◽  
A. E. Volvach ◽  
M. G. Larionov ◽  
G. C. MacLeod ◽  
P. Wolak ◽  
...  
Keyword(s):  
Flux Density ◽  
Observational Data ◽  
Line Width ◽  
Radio Telescopes ◽  
Water Masers ◽  
The Relationship ◽  
Water Maser ◽  
Powerful Flare

Aims. We present our monitoring observations and analysis of water masers associated with W49N taken in 2017 and 2018. A significant flare occurred during these observations. Methods. We used ground-based radio telescopes in Simeiz (RT-22), Torun (RT-32), Medicina (RT-32), Effelsberg (RT-100) with broadband spectrometers. Observational data were collected and processed automatically. Results. We report a powerful flare of the v = +6 km s−1 water maser feature; it increased in over ten months to S1.3 cm = 84 kJy in 2017 December, then decayed to the pre-flare quiescent value of S1.3 cm = 8.7 kJy in 2018 August. We infer that this flaring feature is unsaturated based on the relationship between line width and flux density.

scholarly journals Methanol and water maser observations separate disc and outflow sources in IRAS 19410+2336

2020 ◽  
Vol 493 (3) ◽  
pp. 4442-4452 ◽  
Author(s):  
M S Darwish ◽  
K A Edris ◽  
A M S Richards ◽  
S Etoka ◽  
M S Saad ◽  
...  
Keyword(s):  
Flux Density ◽  
High Mass ◽  
High Angular Resolution ◽  
Mass Star ◽  
Star Forming ◽  
Peak Flux ◽  
Maser Line ◽  
Methanol Masers ◽  
Water Masers ◽  
Water Maser

ABSTRACT We investigate the kinematics of high-mass protostellar objects within the high-mass star-forming region IRAS 19410+2336. We performed high angular resolution observations of 6.7-GHz methanol and 22 GHz water masers using the Multi-Element Radio Linked Interferometer Network (MERLIN) and e-MERLIN interferometers. The 6.7-GHz methanol maser emission line was detected within the ∼16–27 km s−1 velocity range with a peak flux density ∼50 Jy. The maser spots are spread over ∼1.3 arcsec on the sky, corresponding to ∼2800 au at a distance of 2.16 kpc. These are the first astrometric measurements at 6.7 GHz in IRAS 19410+2336. The 22-GHz water maser line was imaged in 2005 and 2019 (the latter with good astrometry). Its velocities range from 13 to ∼29 km s−1. The peak flux density was found to be 18.7 and 13.487 Jy in 2005 and 2019, respectively. The distribution of the water maser components is up to 165 mas, ∼350 au at 2.16 kpc. We find that the Eastern methanol masers most probably trace outflows from the region of millimetre source mm1. The water masers to the West lie in a disc (flared or interacting with outflow/infall) around another more evolved millimetre source (13-s). The maser distribution suggests that the disc lies at an angle of 60° or more to the plane of the sky and the observed line-of-sight velocities then suggest an enclosed mass between 44 M⊙ and as little as 11 M⊙ if the disc is edge-on. The Western methanol masers may be infalling.

scholarly journals New detections of 321 GHz water masers toward late-type stars

2002 ◽  
Vol 206 ◽  
pp. 314-317
Author(s):  
Tarja Liljeström ◽  
Anders Winnberg ◽  
Roy Booth
Keyword(s):  
Water Vapor ◽  
Hot Water ◽  
Late Type ◽  
Vibrationally Excited ◽  
Mira Variable ◽  
Maser Line ◽  
Shock Motion ◽  
Water Masers ◽  
Water Maser

The SEST telescope has been used for a submillimeter water maser survey toward late-type stars. Six new 321 GHz water masers were detected. These, as well as the earlier reported sources, VY CMa and o Cet, were also observed in the vibrationally excited water maser line at 96 GHz. However, only VY CMa and o Cet showed the 96 GHz emission. The line velocity of o Cet is blueshifted, suggesting that the hot water vapor at 96 GHz takes part in the pulsation-shock motion of the Mira variable.

scholarly journals Highly polarized burst of a water maser in Orion-KL

2002 ◽  
Vol 206 ◽  
pp. 92-95
Author(s):  
Shinji Horiuchi ◽  
Osamu Kameya
Keyword(s):  
Magnetic Field ◽  
Flux Density ◽  
Strong Magnetic Field ◽  
Radio Telescope ◽  
Linear Polarization ◽  
Total Flux ◽  
Star Forming ◽  
Intensity Decrease ◽  
Density Decrease ◽  
Water Maser

It has been reported that the 22 GHz water maser in the star forming region Orion-KL has started an outburst in rate 1997 (Omodaka et al. 1998, IAUC 6893). Using Mizusawa radio telescope we started a monitoring observation of the bursting maser. We measured the linear polarization of the maser after the burst, during a phase of rapid flux density decrease. We find that the total flux density of 2.4 × 106 Jy (December 1998) exhibits about 46% linear polarization. Over the next six months we find that the total intensity decrease about two orders of magnitude while the fractional linear polarization gradually fell to 30%. These results suggest that the present bursting phenomenon has an origin similar to the super maser event starting in 1979, and the phenomenon of the extremely bright masers in this region is geometric in nature and related to the strong magnetic field.

scholarly journals Shock Structure of the High-Velocity Water Masers in W 49 N

1998 ◽  
Vol 164 ◽  
pp. 251-252
Author(s):  
T. Liljeström
Keyword(s):  
Magnetic Field ◽  
High Velocity ◽  
Shock Structure ◽  
Shock Models ◽  
Vlbi Data ◽  
Water Masers ◽  
Velocity Water

AbstractMagnetic field parameters and other characteristics of the postshocked gas in W 49 N are derived from a linewidth comparison between the multi-epoch VLBI data of Gwinn and contemporaneous long-term single-dish observations. The observations support predictions of dissociative shock models.

scholarly journals Characterizing maser polarization: effects of saturation, anisotropic pumping, and hyperfine structure

2019 ◽  
Vol 628 ◽  
pp. A14
Author(s):  
Boy Lankhaar ◽  
Wouter Vlemmings
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Scatter Plots ◽  
Polarization Characteristics ◽  
Paramagnetic Molecules ◽  
Water Masers ◽  
Polarization Models ◽  
The Magnetic Field ◽  
Water Maser

Context. The polarization of masers contains information on the magnetic field strength and direction of the regions they occur in. Many maser polarization observations have been performed over the last 30 years. However, versatile maser polarization models that can aide in the interpretation of these observations are not available. Aims. We developed a program suite that can compute the polarization by a magnetic field of any non-paramagnetic maser species at arbitrarily high maser saturation. Furthermore, we investigated the polarization of masers by non-Zeeman polarizing effects. We present a general interpretive structure for maser polarization observations. Methods. We expanded existing maser polarization theories of non-paramagnetic molecules and incorporated them in a numerical modeling program suite. Results. We present a modeling program called CHAracterizes Maser Polarization (CHAMP) that can examine the polarization of masers of arbitrarily high maser saturation and high angular momentum. Hyperfine multiplicity of the maser-transition can also be incorporated. The user is able to investigate non-Zeeman polarizing mechanisms such as anisotropic pumping and polarized incident seed radiation. We present an analysis of the polarization of v = 1 SiO masers and the 22 GHz water maser. We comment on the underlying polarization mechanisms, and also investigate non-Zeeman effects. Conclusions. We identify the regimes where different polarizing mechanisms will be dominant and present the polarization characteristics of the SiO and water masers. From the results of our calculations, we identify markers to recognize alternative polarization mechanisms. We show that comparing randomly generated linear versus circular polarization (pL − pV) scatter-plots at fixed magnetic field strength to the observationally obtained pL − pV scatter can be a promising method of ascertaining the average magnetic field strength of a large number of masers.

scholarly journals 658 GHz vibrationally-excited water masers with the Submillimeter Array

2007 ◽  
Vol 3 (S242) ◽  
pp. 481-488 ◽  
Author(s):  
T. R. Hunter ◽  
K. H. Young ◽  
R. D. Christensen ◽  
M. A. Gurwell
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Phase Transfer ◽  
Physical Region ◽  
Vibrationally Excited ◽  
Maser Emission ◽  
Maser Line ◽  
Water Masers ◽  
Theoretical Considerations ◽  
Water Maser

AbstractDiscovered in 1995 at the Caltech Submillimeter Observatory (CSO), the vibrationally-excited water maser line at 658 GHz (455 micron) is seen in oxygen-rich giant and supergiant stars. Because this maser can be so strong (up to thousands of Janskys), it was very helpful during the commissioning phase of the highest frequency band (620-700 GHz) of the Submillimeter Array (SMA) interferometer. From late 2002 to early 2006, brief attempts were made to search for emission from additional sources beyond the original CSO survey. These efforts have expanded the source count from 10 to 16. The maser emission appears to be quite compact spatially, as expected from theoretical considerations; thus these objects can potentially be used as atmospheric phase calibrators. Many of these objects also exhibit maser emission in the vibrationally-excited SiO maser at 215 GHz. Because both maser lines likely originate from a similar physical region, these objects can be used to test techniques of phase transfer calibration between millimeter and submillimeter bands. The 658 GHz masers will be important beacons to assess the performance of the Atacama Large Millimeter Array (ALMA) in this challenging high-frequency band.

scholarly journals A revised distance to IRAS 16293-2422 from VLBA astrometry of associated water masers

2018 ◽  
Vol 614 ◽  
pp. A20 ◽  
Author(s):  
S. A. Dzib ◽  
G. N. Ortiz-León ◽  
A. Hernández-Gómez ◽  
L. Loinard ◽  
A. J. Mioduszewski ◽  
...  
Keyword(s):  
Stellar System ◽  
Young Star ◽  
Young Stars ◽  
Archival Data ◽  
Trigonometric Parallax ◽  
Maser Line ◽  
Water Masers ◽  
Range Of Values ◽  
Water Maser ◽  
Good Agreement

IRAS 16293-2422 is a very well-studied young stellar system seen in projection towards the L1689N cloud in the Ophiuchus complex. However, its distance is still uncertain; there is a range of values from 120 pc to 180 pc. Our goal is to measure the trigonometric parallax of this young star by means of H2O maser emission. We use archival data from 15 epochs of VLBA observations of the 22.2 GHz water maser line. By modeling the displacement on the sky of the H2O maser spots, we derived a trigonometric parallax of 7.1 ± 1.3 mas, corresponding to a distance of 141−21+30 pc. This new distance is in good agreement with recent values obtained for other magnetically active young stars in the L1689 cloud. We relate the kinematics of these masers with the outflows and the recent ejections powered by source A in the system.

A novel analytical calculation of magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping

2020 ◽  
pp. 1-15
Author(s):  
Jianqi Li ◽  
Yu Zhou ◽  
Jianying Li
Keyword(s):  
Magnetic Field ◽  
Conformal Mapping ◽  
Permanent Magnet ◽  
Flux Density ◽  
Analytical Method ◽  
Electromotive Force ◽  
Analytical Calculation ◽  
Air Gap ◽  
Permanent Magnet Machines ◽  
Peak Value

This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.

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