Skip to main content Accessibility help
×
Home

Variability of masers in circumstellar shells on timescales of decades

  • D. Engels (a1), A. Winnberg (a2), J. Brand (a3) and F. Jiménez-Esteban (a4)

Abstract

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 (1σ).

    • Send article to Kindle

      To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      Variability of masers in circumstellar shells on timescales of decades
      Available formats
      ×

      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      Variability of masers in circumstellar shells on timescales of decades
      Available formats
      ×

      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      Variability of masers in circumstellar shells on timescales of decades
      Available formats
      ×

Copyright

References

Hide All
Baud, B., Habing, H. J., Matthews, H. E., & Winnberg, A. 1981, A&AS 95, 156
Bowers, P. F., Claussen, M. J. & Johnston, K. J. 1993, AJ 105, 284
Brand, J., Baldacci, L. & Engels, D. 2002 in Migenes, V., Reid, M. (eds.), IAU Symp. 206, p. 202
Engels, D., et al. 1999 in Bertre, T. Le et al. (eds.), IAU Symp. 191, p. 373
Engels, D. & Jiménez-Esteban, F. 2007, A&A submitted
Lewis, B. M. 2002, ApJ 576, 445
Winnberg, A., Engels, D., Brand, J., et al. 2007, in preparation
MathJax
MathJax is a JavaScript display engine for mathematics. For more information see http://www.mathjax.org.

Keywords

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed