Masers and Galactic structure: Micro-arcsecond astrometry with the VLBA
Date Issued
2007
Author(s)
Abstract
Astrometric observations with the VLBA with accuracies approaching ~ 10 μas are being conducted in order to better understand the Galaxy. The location of Sgr A* on infrared images can be determined with an accuracy of a few mas, using stars with SiO maser emission as a calibration grid for infrared images. The apparent proper motion of Sgr A*, which is dominated by the effects of the orbit of the Sun around the Galactic center, has been measured with high accuracy. This measurement strongly constrains Θ0R0 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. When combined with infrared results, this provides overwhelming evidence that Sgr A* is a supermassive black hole. Finally, we are engaged in a large project to map the spiral structure and kinematics of the Galaxy. Preliminary trigonometric parallaxes, obtained with the VLBA, to eight massive star forming regions are presented.
Coverage
Astrophysical Masers and their Environments
All editors
Chapman, Jessica M.; Baan, Willem A.
Volume
vol. 3, S242
Start page
348
Conferenece
Astrophysical Masers and their Environments
Conferenece place
Alice Springs, Australia
Conferenece date
March 12-16, 2007
Issn Identifier
1743-9213
Ads BibCode
2007IAUS..242..348R
Rights
open.access
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