Mass-loss variations among carbon-rich AGB variables
Abstract
Near-infrared light curves are presented for 11 large-amplitude carbon variables, covering time periods of 9 to 22yr. The light curves differ greatly among the various stars, although there is some degree of similarity among those with similar mass-loss characteristics. Three Miras with moderately thick dust shells, R For, R Lep and R Vol, exhibit large-amplitude (up to DeltaJ~2mag), erratic changes on top of their normal pulsational variations. The similarity between their light curves and those of R Coronae Borealis stars is noted. Evidence is presented that suggests that carbon-rich dust ejection occurs in a preferred direction, possibly from the equator. In the case of R Lep at least, the preferred direction coincides with the line of sight. Periodic variations of the dust shell, which have previously been suggested for R For, are not confirmed. Three Miras with very thin dust shells, V Cru, TT Cen and RV Cen, show rather little in the way of long-term trends. One of two thick-shelled sources, IZ Peg (CRL 3099), has a pulsation amplitude which has been gradually increasing over the last 16 years. The three semiregular variables, R Scl, GM CMa and IRAS 04067-0922, all show evidence of detached shells. Two of them also have double periods: GM CMa at twice the dominant pulsation period, and R Scl at approximately five times the dominant pulsation period.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 1997
- DOI:
- 10.1093/mnras/288.2.512
- Bibcode:
- 1997MNRAS.288..512W
- Keywords:
-
- STARS: AGB AND POST-AGB;
- STARS: CARBON;
- STARS: LATE-TYPE;
- STARS: MASS-LOSS;
- STARS: VARIABLES: OTHER;
- INFRARED: STARS