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TWINKLING STARS The disappearing SiO masers of W Aql

Published online by Cambridge University Press:  24 July 2012

Sofia Ramstedt
Affiliation:
Argelander Institut für Astronomie, Bonn, Germany email: [email protected]
Wouter Vlemmings
Affiliation:
Onsala Space Observatory, Onsala, Sweden
Shazrene Mohamed
Affiliation:
South African Astronomical Observatory, P.O. Box 9, 7935 Observatory, South Africa
Yoon Kyung Choi
Affiliation:
Max Planck Institut für Radioastronomie, Bonn, Germany
Hans Olofsson
Affiliation:
Onsala Space Observatory, Onsala, Sweden
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Abstract

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W Aql is a binary S-type AGB star showing SiO maser emission. The dust distribution around the star is asymmetric, possibly indicating gravitational interaction between the binary pair. There are indications that the gas distribution also exhibits asymmetries. To investigate the source of the circumstellar structures, we applied for and were rewarded VLBI time to map the distribution of the SiO masers around this source and to constrain the presence and distribution of a possible magnetic field. Using VERA observations we also aim at measuring an accurate parallax to determine the binary separation, however, from showing peak emission of 21 Jy in June 2010, the SiO(1-0) v=1 line at 43 GHz has now disappeared. We find no correlation with the stellar pulsational period.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2012

References

Ramstedt, S., Maercker, M., Olofsson, G., Olofsson, H., & Schöier, F. L. 2011, A&A, 531, 148Google Scholar
Nakashima, J. & Deguchi, S. 2007, ApJ, 669, 446CrossRefGoogle Scholar