Radial velocity monitoring of a sample of barium and S stars using CORAVEL : towards an evolutionary link between barium and S stars ?
Abstract
A sample of 27 southern Ba II and 9 northern S stars has been observed with the radial velocity spectrometer CORAVEL during three seasons. A high proportion (≈89%) of stars with variable radial velocities has been found in both samples. Concernig Ba II stars, there is no doubt about the orbital origin of the observed radial velocity variations. A least 5 S stars show velocity variations originating in orbital motions, while Mira-type pulsations of small amplitude cannot be firmly excluded for 3 more S stars displaying velocity variations with dispersions in the interval 1.0 - 1.5 km s-1. The observations provide additional support to the Ba II-S evolutionary scheme, although a review of other observational data shows that it is probably not possible to totally rule out the currently proposed M-S-C sequence. A binary scenario involving mass transfer and accounting for this dual origin of S stars is proposed.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 1988
- Bibcode:
- 1988A&A...198..187J
- Keywords:
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- Barium;
- Binary Stars;
- Radial Velocity;
- Red Giant Stars;
- S Stars;
- Stellar Evolution;
- Stellar Mass Accretion;
- Velocity Distribution;
- Astrophysics