Patterns in water maser emission of evolved stars on the timescale of decades
Paper in proceeding, 2022

We present our past and current long-term monitoring program of water masers in the circumstellar envelopes of evolved stars, augmented by occasional interferometric observations. Using as example the Mira-variable U Her, we identify three types of variability: periodic (following the optical variation), long-term (years-decades) and short-term irregular (weeks-months). We show there are regions in the maser shell where excitation conditions are favourable, which remain stable for many years. Lifetimes of maser clouds in the wind-acceleration zone are of the order of up to a few years. Much longer lifetimes are found for the peculiar case of a maser cloud outside that zone (as in RT Vir), or in some cases where the motion of spectral features can be followed for the entire 2 decade monitoring period (as in red supergiant VX Sgr).

AGB and post-AGB stars


water masers


J. Brand

Istituto di Radioastronomia

D. Engels

University of Hamburg

Anders Winnberg

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

Proceedings of the International Astronomical Union

1743-9213 (ISSN) 1743-9221 (eISSN)

Vol. 18 319-323

Subject Categories

Astronomy, Astrophysics and Cosmology



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