Proc. IAU volume 13, issue S336, P393-394 2017 DOI: 10.1017/s1743921317009450 View full text
Jan Brand, Dieter Engels, Anders Winnberg

Abstract: For several decades we have been carrying out observations of water masers in the circumstellar envelopes (CSE's) of Mira variables, Red Supergiants (RSG's) and Semi-Regular Variables (SRV's) with the Medicina 32-m and Effelsberg 100-m antennas. The single-dish monitoring observations provide evidence for strong H2O maser profile variations, which likely are connected to structural changes in the maser shells. Such variations include strong flares in intensity lasting several (tens of) months and systemic vel…

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