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 22 GHz Water Maser Survey of the Xinjiang Astronomical Observatory

2012 ◽  
Vol 8 (S287) ◽  
pp. 296-297
Author(s):  
Jian-jun Zhou ◽  
Jarken Esimbek ◽  
Gang Wu
Keyword(s):  
Galactic Plane ◽  
Astronomical Observatory ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Gas Kinematics ◽  
Star Forming Regions ◽  
Water Masers ◽  
Maser Sources ◽  
Water Maser

AbstractWater masers are good tracers of high-mass star-forming regions. Water maser VLBI observations provide a good probe for studying high-mass star formation and galactic structure. We plan to make a blind survey toward the northern Galactic plane in future years using the 25 m radio telescope of the Xinjiang Astronomical Observatory. We will select some water maser sources discovered in the survey and perform high resolution observations to study the gas kinematics close to high-mass protostars.

scholarly journals VLBI multi-epoch water maser observations toward massive protostars

2012 ◽  
Vol 8 (S287) ◽  
pp. 377-385 ◽  
Author(s):  
José M. Torrelles ◽  
José F. Gómez ◽  
Nimesh A. Patel ◽  
Salvador Curiel ◽  
Guillem Anglada ◽  
...  
Keyword(s):  
Massive Star ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Central Engine ◽  
Dynamic Scenario ◽  
Low Mass ◽  
Cepheus A ◽  
Water Maser

AbstractVLBI multi-epoch water maser observations are a powerful tool to study the gas very close to the central engine responsible for the phenomena associated with the early evolution of massive protostars. In this paper we present a summary of the main observational results obtained toward the massive star-forming regions of Cepheus A and W75N. These observations revealed unexpected phenomena in the earliest stages of evolution of massive objects (e.g., non-collimated “short-lived” pulsed ejections in different massive protostars), and provided new insights in the study of the dynamic scenario of the formation of high-mass stars (e.g., simultaneous presence of a jet and wide-angle outflow in the massive object Cep A HW2, similar to what is observed in low-mass protostars). In addition, with these observations it has been possible to identify new, previously unseen centers of high-mass star formation through outflow activity.

scholarly journals A Circumstellar Disk toward the High-mass Star-forming Region IRAS 23033+5951

2012 ◽  
Vol 8 (S287) ◽  
pp. 192-193
Author(s):  
M. A. Trinidad ◽  
T. Rodríguez ◽  
V. Migenes
Keyword(s):  
High Mass ◽  
Circumstellar Disk ◽  
Mass Star ◽  
Star Forming ◽  
Model Based ◽  
Kinematical Model ◽  
Water Masers ◽  
Water Maser

AbstractWe present water maser observations toward IRAS 23033+5951 carried out with the VLA-EVLA in the A configuration. In order to study the spatio-kinematical distribution of the water masers detected in the region, we made a simple geometrical and kinematical model based on the conical equation. We find that the water masers are tracing a rotating and contracting circumstellar disk of about 110 AU around a very young source of 18 M⊙, which has not enough ionizing photons to be detected at centimeter wavelengths.

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 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.

New water maser source near HW3d in the massive star-forming region Cepheus A

2017 ◽  
Vol 13 (S336) ◽  
pp. 297-298
Author(s):  
Jeong-Sook Kim ◽  
Soon-Wook Kim
Keyword(s):  
Radio Continuum ◽  
Young Stellar Objects ◽  
High Mass ◽  
Mass Star ◽  
Stellar Objects ◽  
Star Forming ◽  
Star Forming Regions ◽  
Molecular Outflow ◽  
Cepheus A ◽  
Water Maser

AbstractCepheus A is the second nearest high mass star-forming region after Orion. It is characterized by the presence of several phenomena, such as a complex molecular outflow, and multiple radio continuum sources, known as HW sources. The radio continuum and water maser emission have been detected toward HW2, HW3b and HW3d regions, and all of them are considered harboring young stellar objects. In 2014, we performed KaVA observations and detected a new bright maser feature, ~700 mas apart from HW3d, which has not been detected with previous VLBI observations. The relative proper motion of the new maser feature is faster than other regions. It can be a clue for a newly forming star. Alternatively, it may be caused by outflow shock from the star-forming regions such as HW3d or HW3c.

A Circumstellar Disk in IRAS 23151+5912?

2017 ◽  
Vol 13 (S336) ◽  
pp. 315-316
Author(s):  
Miguel A. Trinidad ◽  
Tatiana Rodríguez-Esnard ◽  
Josep M. Masqué
Keyword(s):  
Radio Continuum ◽  
High Mass ◽  
Circumstellar Disk ◽  
Mass Star ◽  
Hii Region ◽  
Star Forming ◽  
Continuum Source ◽  
Water Masers ◽  
Water Maser ◽  
The Continuum

AbstractWe present radio continuum and water maser observations toward the high-mass star-forming region IRAS 23151+5912 from the VLA and VLBA archive, respectively. We detected a continuum source, which seems to be a hypercompact HII region. In addition, a water maser group about 4″ south from the continuum source was detected. We present preliminary results of the analysis of three observations epochs of the water masers, which are tracing an arc-like structure. However, its kinematics is quite complex, since while one section of the structure seems to be moving away from one center, another section seems to be approaching.

scholarly journals Challenging shock models with SOFIA OH observations in the high-mass star-forming region Cepheus A

2015 ◽  
Vol 585 ◽  
pp. A45 ◽  
Author(s):  
A. Gusdorf ◽  
R. Güsten ◽  
K. M. Menten ◽  
D. R. Flower ◽  
G. Pineau des Forêts ◽  
...  
Keyword(s):  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Shock Models ◽  
Cepheus A

scholarly journals RadioAstron space-VLBI project: studies of masers in star forming regions of our Galaxy and megamasers in external galaxies

2017 ◽  
Vol 13 (S336) ◽  
pp. 417-421 ◽  
Author(s):  
A. M. Sobolev ◽  
N. N. Shakhvorostova ◽  
A. V. Alakoz ◽  
W. A. Baan
Keyword(s):  
Angular Resolution ◽  
Nearby Galaxy ◽  
Major Step ◽  
Maser Emission ◽  
Star Forming ◽  
Star Forming Regions ◽  
The Galaxy ◽  
External Galaxies ◽  
First Time ◽  
Water Maser

AbstractObservations of the masers in the course of RadioAstron mission yielded detections of fringes for a number of sources in both water and hydroxyl maser transitions. Several sources display numerous ultra-compact details. This proves that implementation of the space VLBI technique for maser studies is possible technically and is not always prevented by the interstellar scattering, maser beaming and other effects related to formation, transfer, and detection of the cosmic maser emission. For the first time, cosmic water maser emission was detected with projected baselines exceeding Earth Diameter. It was detected in a number of star-forming regions in the Galaxy and two megamaser galaxies NGC 4258 and NGC 3079. RadioAstron observations provided the absolute record of the angular resolution in astronomy. Fringes from the NGC 4258 megamaser were detected on baseline exceeding 25 Earth Diameters. This means that the angular resolution sufficient to measure the parallax of the water maser source in the nearby galaxy LMC was directly achieved in the cosmic maser observations. Very compact features with angular sizes about 20\muas\, have been detected in star-forming regions of our Galaxy. Corresponding linear sizes are about 5-10 million kilometers. So, the major step from milli- to micro-arcsecond resolution in maser studies is achieved by the RadioAstron mission. The existence of the features with extremely small angular sizes is established. Further implementations of the space–VLBI maser instrument for studies of the nature of cosmic objects, studies of the interaction of extremely high radiation field with molecular material and studies of the matter on the line of sight are planned.

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.

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