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Radio and IR interferometry of SiO maser stars

Published online by Cambridge University Press:  24 July 2012

Markus Wittkowski ,
David A. Boboltz ,
Malcolm D. Gray ,
Elizabeth M. L. Humphreys ,
Iva Karovicova  and
Michael Scholz
Markus Wittkowski
Affiliation:
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
David A. Boboltz
Affiliation:
US Naval Observatory, 3450 Massachusetts Avenue, NW, Washington, DC 20392-5420, USA
Malcolm D. Gray
Affiliation:
Jodrell Bank Centre for Astrophysics, Alan Turing Building, University of Manchester, Manchester M13 9PL, UK
Elizabeth M. L. Humphreys
Affiliation:
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
Iva Karovicova
Affiliation:
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
Michael Scholz
Affiliation:
Zentrum für Astronomie der Universität Heidelberg (ZAH), Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney NSW 2006, Australia
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Abstract

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Radio and infrared interferometry of SiO maser stars provide complementary information on the atmosphere and circumstellar environment at comparable spatial resolution. Here, we present the latest results on the atmospheric structure and the dust condensation region of AGB stars based on our recent infrared spectro-interferometric observations, which represent the environment of SiO masers. We discuss, as an example, new results from simultaneous VLTI and VLBA observations of the Mira variable AGB star R Cnc, including VLTI near- and mid-infrared interferometry, as well as VLBA observations of the SiO maser emission toward this source. We present preliminary results from a monitoring campaign of high-frequency SiO maser emission toward evolved stars obtained with the APEX telescope, which also serves as a precursor of ALMA images of the SiO emitting region. We speculate that large-scale long-period chaotic motion in the extended molecular atmosphere may be the physical reason for observed deviations from point symmetry of atmospheric molecular layers, and for the observed erratic variability of high-frequency SiO maser emission.

Keywords

masersradiative transferturbulencetechniques: interferometricstars: AGB and post-AGBstars: atmospheresstars: circumstellar matterstars: fundamental parametersstars: mass losssupergiants
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 8 , Symposium S287: Cosmic Masers - from OH to H0 , January 2012 , pp. 209 - 216
Copyright
Copyright © International Astronomical Union 2012

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