Variability of masers in circumstellar shells on timescales of decades
Paper in proceedings, 2007

Based on a 15-20 year long monitoring program of H2O masers and new observations of OH masers discovered 35 years ago, we studied the variability of maser emission in AGB stars over timescales of decades. The H2O maser features in the semi-regular variable stars RX Boo and SV Peg, and of the Mira stars U Her and R Cas, showed strong fluctuations superposed in case of the Mira stars on regular variations due to the pulsation of the stars. The spatial distribution of the emission regions in RX Boo and U Her showed deviations from spherical symmetry, which remained unchanged over >10 years. We conclude that the spatial asymmetry is determined by the underlying asymmetry of the mass loss process. There is no evidence that mass loss rates or the wind geometry in these stars have varied over the last 20 years. In 2005 we re-detected at 1612 MHz the 114 OH/IR stars discovered before 1978, implying an OH maser lifetime of >2800 years (1). © 2008 International Astronomical Union.

Stars: AGB and post-AGB

Stars: late-type

Masers

Author

D. Engels

Universität Hamburg

Anders Winnberg

Chalmers, Earth and Space Sciences

J. Brand

Istituto di Radioastronomia

F. Jiménez-Esteban

Spanish National Observatory (OAN)

Proceedings of the International Astronomical Union

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

Vol. 3 S242 318-319

Subject Categories

Meteorology and Atmospheric Sciences

Astronomy, Astrophysics and Cosmology

Environmental Sciences

DOI

10.1017/S174392130701321X

More information

Latest update

3/10/2020