scholarly journals Parallax of Star-forming Region G027.22+0.14

2022 ◽  
Vol 163 (2) ◽  
pp. 54
Author(s):  
S. B. Bian ◽  
Y. Xu ◽  
J. J. Li ◽  
Y. W. Wu ◽  
B. Zhang ◽  
...  
Keyword(s):  
Proper Motion ◽  
High Mass ◽  
Mass Star ◽  
Proper Motions ◽  
Star Forming ◽  
Long Baseline ◽  
Trigonometric Parallax ◽  
Peculiar Motion ◽  
Very Long Baseline Array ◽  
Lower Luminosity

Abstract Using the Very Long Baseline Array, we measured the trigonometric parallax and proper motions toward a 6.7 GHz methanol maser in the distant high-mass star-forming region G027.22+0.14. The distance of this source is determined to be 6.3 − 0.5 + 0.6 kpc. Combining its Galactic coordinates, radial velocity, and proper motion, we assign G027.22+0.14 to the far portion of the Norma arm. The low peculiar motion and lower luminosity of G027.22+0.14 support the conjecture by Immer et al. that low-luminosity sources tend to have low peculiar motions.

scholarly journals The distance to G59.7+0.1 and W3OH

2007 ◽  
Vol 3 (S248) ◽  
pp. 214-216
Author(s):  
Y. Xu ◽  
M. J. Reid ◽  
K. M. Menten ◽  
X. W. Zheng ◽  
A. Brunthaler ◽  
...  
Keyword(s):  
High Mass ◽  
Radio Sources ◽  
Mass Star ◽  
Proper Motions ◽  
Extragalactic Radio Sources ◽  
Star Forming ◽  
Long Baseline ◽  
Methanol Masers ◽  
Very Long Baseline Array

AbstractWe have measured the distance to the high-mass star-forming region G59.7+0.1 (IRAS 19410+2336) and W3OH. Their distances, 2.20 ± 0.11 kpc and 1.95 ± 0.04 kpc, respectively, were determined by triangulation using Very Long Baseline Array (VLBA) observations of 12.2 GHz methanol masers phase-referenced to compact extragalactic radio sources. In addition to the distances, we have also obtained their proper motions.

scholarly journals Rotational parallaxes of nearby galaxies

2012 ◽  
Vol 8 (S289) ◽  
pp. 226-226
Author(s):  
Andreas Brunthaler
Keyword(s):  
High Mass ◽  
Mass Star ◽  
Proper Motions ◽  
Star Forming ◽  
Star Forming Regions ◽  
Long Baseline ◽  
First Results ◽  
Systematic Effects ◽  
Nearby Galaxies ◽  
Water Masers

AbstractAccurate geometric distances, which are inherently free of systematic effects are of very great importance for an independent recalibration of extragalactic distance estimators. Local Group galaxies are close enough for both primary and secondary distance indicators to be readily isolated in ground- and space-based observations. Astrometric accuracies of a few micro-arcseconds based on Very Long Baseline Interferometry (VLBI) observations of water masers in high-mass star-forming regions in nearby galaxies allow a measurement of the proper motions of these masers. Since these high-mass star-forming regions rotate with the galaxies, one can deduce a rotational parallax by comparing the known rotation curve with the proper motions of the masers. I provide an update of our previous rotation parallax of M33 and show first results of observations of the recently discovered water masers in the Andromeda galaxy (M31).

scholarly journals Intrinsic Sizes of the W3 (OH) Masers via Short Time Scale Variability

2012 ◽  
Vol 8 (S287) ◽  
pp. 465-469 ◽  
Author(s):  
Tanmoy Laskar ◽  
W. M. Goss ◽  
B. Ashley Zauderer
Keyword(s):  
Time Scale ◽  
High Mass ◽  
Short Time Scale ◽  
Mass Star ◽  
Star Forming ◽  
Long Baseline ◽  
Interstellar Scintillation ◽  
Maser Line ◽  
Short Time ◽  
Very Long Baseline Array

AbstractWe present a study of short time-scale variability of OH masers within a contiguous 15-hour Very Long Baseline Array observation of the high-mass star-forming region, W3 (OH). With an angular resolution of ~7 mas and a velocity resolution of 53 m s−1, we isolate emission from masers in the field into individual Gaussian-shaped components, each a few milliarcseconds in size. We compute dynamic spectra for individual maser features with a time resolution of 1 minute by fitting for the flux density of all sources in the field simultaneously in the uv-domain. We isolate intrinsic maser variability from interstellar scintillation and instrumental effects. We find fluctuations in the maser line shape on time scales of 5 to 20 minutes, corresponding to maser column lengths of 0.5 to 2.0 Astronomical Units.

scholarly journals The distance to G59.7+0.1

2007 ◽  
Vol 3 (S242) ◽  
pp. 374-375
Author(s):  
Y. Xu ◽  
M. J. Reid ◽  
K. M. Menten ◽  
A. Brunthaler ◽  
X. W. Zheng ◽  
...  
Keyword(s):  
High Mass ◽  
Radio Sources ◽  
Mass Star ◽  
Extragalactic Radio Sources ◽  
Star Forming ◽  
Long Baseline ◽  
Infra Red ◽  
Methanol Masers ◽  
Very Long Baseline Array

AbstractWe have measured the distance to the high-mass star-forming region G59.7+0.1, which harbors the far-infra-red source IRAS 19410+2336. The distance is 2.20 ± 0.11 kpc and was determined by triangulation using Very Long Baseline Array (VLBA) observations of 12.2 GHz methanol masers phase-referenced to two compact extragalactic radio sources.

scholarly journals Trigonometric Parallax of the Protoplanetary Nebula OH 231.8+4.2

2012 ◽  
Vol 8 (S287) ◽  
pp. 407-410 ◽  
Author(s):  
Y. K. Choi ◽  
A. Brunthaler ◽  
K. M. Menten ◽  
M. J. Reid
Keyword(s):  
Spatial Distribution ◽  
Proper Motion ◽  
Bipolar Outflow ◽  
Long Baseline ◽  
Internal Motions ◽  
Trigonometric Parallax ◽  
Protoplanetary Nebula ◽  
Very Long Baseline Array

AbstractWe report a trigonometric parallax measurement for the H2O masers around the protoplanetary nebula OH 231.8+4.2 carried out with the Very Long Baseline Array (VLBA). Based on astrometric monitoring for 1 year, we measured a parallax of 0.65 ± 0.01 mas, corresponding to a distance of 1.54 +0.02−0.01 kpc. The spatial distribution of H2O masers is consistent with that found in the previous studies. After removing the average proper motion of 1.4 mas yr−1, corresponding to 10 km s−1, the internal motions of the H2O maser spots indicate a bipolar outflow.

scholarly journals The radial velocity acceleration of the 6.7 GHz methanol maser in Mon R2 IRS3

2012 ◽  
Vol 8 (S287) ◽  
pp. 190-191
Author(s):  
K. Sugiyama ◽  
K. Fujisawa ◽  
N. Shino ◽  
A. Doi
Keyword(s):  
Radial Velocity ◽  
High Mass ◽  
Mass Star ◽  
Spectral Features ◽  
Proper Motions ◽  
Infrared Source ◽  
Young Stellar Object ◽  
Star Forming ◽  
Methanol Maser ◽  
Methanol Masers

AbstractWe present the radial velocity acceleration of the 6.7 GHz methanol maser in a high-mass star-forming region Monoceros R2 (Mon R2). The methanol maser is associated with an infrared source IRS3. The methanol maser of Mon R2 shows at least three spectral features having radial velocities (Vlsr) of 10.8, 12.7, and 13.2 km s−1. The radial velocity of a feature at Vlsr = 12.7 km s−1 has changed during ten years from Aug. 1999 to Oct. 2009, corresponding to an acceleration of 0.08 km s−1 yr−1. We observed the 6.7 GHz methanol masers of Mon R2 in Oct. 2008 using the Japanese VLBI Network (JVN). Compared with the previous VLBI image obtained in Nov. 1998 using the European VLBI Network (EVN), the maser feature at Vlsr = 12.7 km s−1 showed relative proper motions of ~2.5 mas yr−1 (about 10 km s−1 at 0.83 kpc) toward the intensity peak of IRS3. The radial velocity acceleration could be caused by an inflow from a disk or envelope around a high-mass young stellar object (YSO) at IRS3.

scholarly journals 10 years of 12.2 GHz methanol maser VLBI observations towards NGC 7538 IRS1 N: proper motions and maser saturation

2012 ◽  
Vol 8 (S287) ◽  
pp. 186-187 ◽  
Author(s):  
Michele Pestalozzi ◽  
Anders Jerkstrand ◽  
John Conway
Keyword(s):  
Proper Motion ◽  
Central Peak ◽  
Time Span ◽  
High Mass ◽  
Mass Star ◽  
Proper Motions ◽  
Motion Signal ◽  
Spatial Features ◽  
Vlbi Observations ◽  
Peak Flux

AbstractWe present the outcomes of the consistent analysis of 6 epochs of VLBA 12.2 GHz data obtained between 1995 and 2005 towards the known high-mass star formation reigon NGC7538 IRS1 N. Our analysis concentrates on the study of the main spectral/spatial feature, which is 20 VLBA synthesized beams in size with a distinct velocity gradient. We looked for proper motion signals relative to the central peak which, in an edge-on disc framework, is expected to be stationary. We also study the peak flux and the spatial brightness profile of the main maser feature searching for maser variability. Our results are twofold: we detect a clear proper motion signal of three spatial features (0.21, 0.1, 0.65 mas yr−1) and conclude that these can be made consistent with previous modelling of a Keplerian disc seen edge-on around a high-mass protostar. We further detect a consistent decrease of the peak flux over the time-span 1995-2005 (~ 5.4 Jy yr−1), confirmed when taking into account earlier data (1986, 1987) as well as by the 6.7 GHz maser emission. Also, the width of the spatial brightness profile of the main feature seems to decrease between 1995 and 2005 by some 50%. We consider these observables as clear signs of partial maser saturation.

scholarly journals VLBA determinations of the distances to nearby star-forming regions

2007 ◽  
Vol 3 (S248) ◽  
pp. 186-189 ◽  
Author(s):  
L. Loinard ◽  
R. M. Torres ◽  
A. J. Mioduszewski ◽  
L. F. Rodríguez
Keyword(s):  
Young Stars ◽  
Line Of Sight ◽  
Nearby Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Long Baseline ◽  
Trigonometric Parallax ◽  
Linear Extent ◽  
The Mean ◽  
Very Long Baseline Array

AbstractUsing phase-referenced multi-epoch Very Long Baseline Array observations, we have measured the trigonometric parallax of several young stars in the Taurus and Ophiuchus star-forming regions with unprecedented accuracy. The mean distance to the Taurus complex was found to be about 140 pc, and its depth around 20 pc, comparable to the linear extent of Taurus on the sky. In Ophiuchus, 4 sources have been observed so far. Two of them were found to be at about 160 pc (the distance traditionally attributed to Ophiuchus), while the other 2 are at about 120 pc. Since the entire Ophiuchus complex is only a few parsecs across, this difference is unlikely to reflect the depth of the region. Instead, we argue that two physically unrelated sites of star-formation are located along the line of sight toward Ophiuchus.

scholarly journals Distance and Maser Outflows of the Galactic Star-forming Region W51 Main/South

2012 ◽  
Vol 8 (S287) ◽  
pp. 423-424 ◽  
Author(s):  
Mayumi Sato ◽  
Mark J. Reid ◽  
Andreas Brunthaler ◽  
Karl M. Menten
Keyword(s):  
Massive Star ◽  
Young Stellar Objects ◽  
Small Range ◽  
Stellar Objects ◽  
Maser Emission ◽  
Star Forming ◽  
Star Forming Regions ◽  
Long Baseline ◽  
Trigonometric Parallax ◽  
Very Long Baseline Array

AbstractWe report on high-resolution astrometry of 22 GHz H2O maser emission in the Galactic massive star-forming region W51 Main/South using the Very Long Baseline Array. We measured the trigonometric parallax of W51 Main/South to be 0.185 ± 0.010 mas, corresponding to a distance of 5.41+0.31−0.28 kpc. The H2O maser emission in W51 Main/South traces four powerful bipolar outflows within a 0.4 pc size region, three of which are associated with dusty molecular hot cores and/or hyper- or ultra-compact Hii regions. The maser outflows in W51 Main/South have a relatively small range of internal 3D speeds, suggesting that multiple speed maser outflows in other Galactic massive star-forming regions may come from separate young stellar objects closely spaced on the sky.

scholarly journals Anomalous peculiar motions of high-mass young stars in the Scutum spiral arm

2019 ◽  
Vol 632 ◽  
pp. A123 ◽  
Author(s):  
K. Immer ◽  
J. Li ◽  
L. H. Quiroga-Nuñez ◽  
M. J. Reid ◽  
B. Zhang ◽  
...  
Keyword(s):  
Spiral Structure ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Trigonometric Parallax ◽  
Motion Measurements ◽  
Methanol Masers ◽  
Galactic Longitude ◽  
Spiral Arm

We present trigonometric parallax and proper motion measurements toward 22 GHz water and 6.7 GHz methanol masers in 16 high-mass star-forming regions. These sources are all located in the Scutum spiral arm of the Milky Way. The observations were conducted as part of the Bar and Spiral Structure Legacy (BeSSeL) survey. A combination of 14 sources from a forthcoming study and 14 sources from the literature, we now have a sample of 44 sources in the Scutum spiral arm, covering a Galactic longitude range from 0° to 33°. A group of 16 sources shows large peculiar motions of which 13 are oriented toward the inner Galaxy. A likely explanation for these high peculiar motions is the combined gravitational potential of the spiral arm and the Galactic bar.

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