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Slow variability and circumstellar shells of red variable stars

Published online by Cambridge University Press:  04 August 2017

T. Lloyd Evans
T. Lloyd Evans*
Affiliation:
South African Astronomical Observatory P.O. Box 9 Observatory 7935 Cape South Africa

Extract

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Infrared photometry shows that while all RV Tauri stars have circumstellar dust shells, the RVb stars with slow cyclic variations in mean light as well as the 30–100 day variations common to all RV stars have more hot dust close to the star (Lloyd Evans 1985). Many M giant stars which are variables of semiregular type also show long-period variations in the mean light (O'Connell 1933; Payne-Gaposchkin 1954), with a roughly constant ratio between the two periods. Payne-Gaposchkin (1954) found P2/P1 ~9.4 for red variables of type M and P2/P1 ~19.4 for stars of type F-K, most of which are FV Tauri stars. Re-analysis using the more extensive data available now indicates P2/P1 ~10 for the M giants and P2/P1 ~15 for the FV Tauri stars. The nature of the long-period variability is unknown (Wood 1975).

Type
Circumstellar Dust and Chemistry
Information
Symposium - International Astronomical Union , Volume 122: Circumstellar Matter , 1987 , pp. 541 - 542
Copyright
Copyright © Reidel 1987 

References

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