Trigonometric Parallaxes of Star-forming Regions beyond the Tangent Point of the Sagittarius Spiral Arm

AbstractWe present a model for hydrodynamic + N-body simulations of star cluster formation and evolution using AMUSE. Our model includes gas dynamics, star formation in regions of dense gas, stellar evolution and a galactic tidal spiral potential, thus incorporating most of the processes that play a role in the evolution of star clusters.We test our model on initial conditions of two colliding molecular clouds as well as a section of a spiral arm from a previous galaxy simulation.

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TRIGONOMETRIC PARALLAXES TO STAR-FORMING REGIONS WITHIN 4 kpc OF THE GALACTIC CENTER

The Astrophysical Journal ◽

10.1088/0004-637x/781/2/108 ◽

2014 ◽

Vol 781 (2) ◽

pp. 108 ◽

Cited By ~ 70

Author(s):

A. Sanna ◽

M. J. Reid ◽

K. M. Menten ◽

T. M. Dame ◽

B. Zhang ◽

...

Keyword(s):

Galactic Center ◽

Star Forming ◽

Star Forming Regions ◽

Trigonometric Parallaxes

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Galactic structure from trigonometric parallaxes of star-forming regions

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312021369 ◽

2012 ◽

Vol 8 (S289) ◽

pp. 188-193 ◽

Cited By ~ 5

Author(s):

Mark J. Reid

Keyword(s):

Interstellar Dust ◽

Milky Way ◽

Galactic Center ◽

Star Forming ◽

Fundamental Parameters ◽

Star Forming Regions ◽

Long Baseline ◽

The Galaxy ◽

Trigonometric Parallaxes ◽

3D Information

AbstractRecently, astrometric accuracy approaching ~ 10 μas has become routinely possible with Very Long Baseline Interferometry. Since, unlike at optical wavelengths, interstellar dust is transparent at radio wavelengths, parallaxes and proper motions can now be measured for massive young stars (with maser emission) across the Galaxy, enabling direct measurements of the spiral structure of the Milky Way. Fitting the full 3D position and velocity vectors to a simple model of the Galaxy yields extremely accurate values for its fundamental parameters, including the distance to the Galactic Center, R0=8.38 ± 0.18 kpc, and circular rotation at the Solar Circle, Θ0 = 243 ± 7 km s−1. The rotation curve of the Milky Way, based for the first time on ‘gold standard’ distances and complete 3D information, appears to be very flat.

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TRIGONOMETRIC PARALLAXES OF MASSIVE STAR-FORMING REGIONS: III. G59.7+0.1 AND W 51 IRS2

The Astrophysical Journal ◽

10.1088/0004-637x/693/1/413 ◽

2009 ◽

Vol 693 (1) ◽

pp. 413-418 ◽

Cited By ~ 92

Author(s):

Y. Xu ◽

M. J. Reid ◽

K. M. Menten ◽

A. Brunthaler ◽

X. W. Zheng ◽

...

Keyword(s):

Massive Star ◽

Star Forming ◽

Star Forming Regions ◽

Trigonometric Parallaxes

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Star Formation in the Large Magellanic Cloud

Symposium - International Astronomical Union ◽

10.1017/s0074180900096315 ◽

1987 ◽

Vol 115 ◽

pp. 521-533

Author(s):

J. V. Feitzinger

Keyword(s):

Star Formation ◽

Large Magellanic Cloud ◽

Radio Continuum ◽

Physical Parameters ◽

Formation Processes ◽

Star Forming ◽

Star Forming Regions ◽

Scale Structures ◽

And Cluster Analysis ◽

Spiral Arm

Methods used in pattern recognition and cluster analysis are applied to investigate the spatial distribution of the star forming regions. The fractal dimension of these structures is deduced. The new 21 cm, radio continuum (1.4 GHz) and IRAS surveys reveal scale structures of 700 pc to 1500 pc being identical with the optically identified star forming sites. The morphological structures delineated by young stars reflect physical parameters which determine the star formation in this galaxy. The formation of spiral arm filaments is understandable by stochastic selfpropagating star formation processes.

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Micro-arcsecond astrometry with the VLBA

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308018929 ◽

2007 ◽

Vol 3 (S248) ◽

pp. 141-147 ◽

Cited By ~ 2

Author(s):

M. J. Reid

Keyword(s):

Galactic Center ◽

Galactic Plane ◽

Proper Motions ◽

Star Forming ◽

Star Forming Regions ◽

The Galaxy ◽

Trigonometric Parallaxes ◽

Sgr A ◽

Definition Of ◽

Almost All

AbstractThe VLBA is now achieving parallaxes and proper motions with accuracies approaching the micro-arcsecond domain. The apparent proper motion of Sgr A*, which reflects the orbit of the Sun around the Galactic center, has been measured with high accuracy. This measurement strongly constrains Θ0/R0 and offers a dynamical definition of the Galactic plane with Sgr A*at its origin. The intrinsic motion of Sgr A*is very small and comparable to that expected for a supermassive black hole. Trigonometric parallaxes and proper motions for a number of massive star forming regions (MSFRs) have now been measured. For almost all cases, kinematic distances exceed the true distances, suggesting that the Galactic parameters, R0 and Θ0, are inaccurate. Solutions for the Solar Motion are in general agreement with those obtained from Hipparcos data, except that MSFRs appear to be rotating slower than the Galaxy. Finally, the VLBA has been used to measure extragalactic proper motions and to map masers in distant AGN accretion disks, which will yield direct estimates of H0.

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