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Astrometry of SiO Masers: First detections of circumstellar SiO maser emission at λ = 7 mm using three European VLBI stations

Published online by Cambridge University Press:  12 April 2016

F. Colomer
Affiliation:
Onsala Space Observatory, S-439 00 Onsala, Sweden Centro Astronómico de Yebes, Apartado 148, 19080-Guadalajara, Spain
D. Graham
Affiliation:
Max-Planck Institut für Radioastronomie, D-5900 Bonn, Germany
T. Krichbaum
Affiliation:
Max-Planck Institut für Radioastronomie, D-5900 Bonn, Germany
B.O. Rönnäng
Affiliation:
Onsala Space Observatory, S-439 00 Onsala, Sweden
P. de Vicente
Affiliation:
Centro Astronómico de Yebes, Apartado 148, 19080-Guadalajara, Spain
A. Barcia
Affiliation:
Centro Astronómico de Yebes, Apartado 148, 19080-Guadalajara, Spain
R.S. Booth
Affiliation:
Onsala Space Observatory, S-439 00 Onsala, Sweden
A. Witzel
Affiliation:
Max-Planck Institut für Radioastronomie, D-5900 Bonn, Germany
J. Gómez-González
Affiliation:
Centro Astronómico de Yebes, Apartado 148, 19080-Guadalajara, Spain
A. Baudry
Affiliation:
Observatoire de Bordeaux, 33270-Floriac, France

Extract

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The positions of circumstellar molecular masers relative to each other, to the central star, and to the compact extragalactic sources are of astrophysical and astrometrical interest. The SiO masers at λ = 7 mm are especially interesting as the maser spots are located very close to the photosphere of the star. For astrometry we would like to see a proper distribution of the maser spots and several epochs of observations in order to estimate the position of the central star and eventual motions of the spots.

The optical position of this star can be determined with ground-based astrometric facilities, and many of the stars showing SiO emission are in the Hipparcos catalogue. A link between the Optical and Radio Reference Frames is achieved in a second step relating the maser spot positions to the Extragalactic Reference Frame (EGRF) established with VLBI (Baudry et al., 1984).

Type
VLBI Imaging
Copyright
Copyright © Astronomical Society of the Pacific 1991

References

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