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Signposts of transitional phases on the Asymptotic Giant Branch

Published online by Cambridge University Press:  07 February 2024

S. Etoka Open the ORCID record for S. Etoka [Opens in a new window]
S. Etoka*
Affiliation:
Jodrell Bank Centre of Astrophysics, Manchester, UK.
*
Sandra.Etoka@googlemail.com
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Abstract

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When low- and intermediate-mass stars pass through the Asymptotic Giant Branch (AGB) they experience dramatic changes in their circumstellar shell (CSE) influenced by their mass loss, the possible presence of a (closeby) companion and the magnetic field. Masers, well spread in this environment, provide a powerful tool to reveal the CSE changes occurring when the stars undergo a transitional phase on the AGB. These can be indirect, via for instance the modification of the pumping conditions or a direct consequence of e.g. a companion and/or of the magnetic field. Evidences of such changes have been observed towards Miras, materialized by strong - both in intensity and degree of polarisation - (OH) flaring events and towards stars believed to be transitioning from the Mira to the OH/IR phase, showing an unusual high degree of polarisation. How OH maser emission can be used as a signpost of transitional phases along the AGB is explored.

Keywords

masersstars: AGB and post-AGBstar: evolutionpolarizationcircumstellar matter
Type
Contributed Paper
Information
Proceedings of the International Astronomical Union , Volume 18 , Symposium S380: Cosmic Masers: Proper Motion toward the Next-Generation Large Projects , December 2022 , pp. 347 - 350
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Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of International Astronomical Union

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