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VLBA observations of the 7mm SiO masers in TX Cam and R Cas

Published online by Cambridge University Press:  03 August 2017

Jiyune Yi ,
Roy S. Booth ,
John E. Conway ,
Anders Winnberg  and
Phillip J. Diamond
Jiyune Yi
Affiliation:
Onsala Space Observatory, Chalmers University of Technology, 43992, Onsala, Sweden
Roy S. Booth
Affiliation:
Onsala Space Observatory, Chalmers University of Technology, 43992, Onsala, Sweden
John E. Conway
Affiliation:
Onsala Space Observatory, Chalmers University of Technology, 43992, Onsala, Sweden
Anders Winnberg
Affiliation:
Onsala Space Observatory, Chalmers University of Technology, 43992, Onsala, Sweden
Phillip J. Diamond
Affiliation:
University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL

Abstract

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Simultaneous VLBI observations of the SiO masers of the J = 1 → 0 rotational line in the v = 1 and v = 2 vibrational levels toward Mira variables are presented. Because SiO maser lines are formed deep in circumstellar envelopes they serve as a unique tool to study the innermost envelopes of evolved stars. Although the first interpretation of SiO maser emission was made in 1974, observational features are only partially explained by models which have been suggested since then. Positional coincidence of the J = 1 → 0 masers of v = 1 and v = 2 has been argued as a way to distinguish among the maser pumping models, but it requires simultaneous observations of the two lines using high resolution. We have developed the technique for such observations during the last few years and here we report successful results of our simultaneous observations of the SiO v = 1 and v = 2 J = 1 → 0 masers using the Very Long Baseline Array (VLBA). We discuss the pumping mechanism in terms of our observational results.

Type
Part 2. Stellar Masers
Information
Symposium - International Astronomical Union , Volume 206: Cosmic Masers: From Protostars to Blackholes , 2002 , pp. 274 - 277
Copyright
Copyright © Astronomical Society of the Pacific 2002 

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