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Distance and Size of the Red Hypergiant NML Cyg

Published online by Cambridge University Press:  24 July 2012

B. Zhang
Affiliation:
Max-Plank-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany email: bzhang@mpifr.de Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China
M. J. Reid
Affiliation:
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
K. M. Menten
Affiliation:
Max-Plank-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany email: bzhang@mpifr.de
X. W. Zheng
Affiliation:
Department of Astronomy, Nanjing University, 22 Hankou Road, Nanjing 210093, China
A. Brunthaler
Affiliation:
Max-Plank-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany email: bzhang@mpifr.de
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Abstract

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We present astrometric results of phase-referencing VLBI observations of 22 GHz H2O maser and 43 GHz SiO maser emission towards the red hypergiant NML Cyg using VLBA. We obtained an annual parallax of 0.62 ± 0.04 mas, corresponding to a distance of 1.61+0.13−0.11 kpc. With a VLA observation in its largest (A) configuration at 43 GHz, we barely resolve the radio photosphere of NML Cyg, and find a uniform-disk diameter of 44 ± 16 mas.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2012

References

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