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Astron. Astrophys. 363, 660-666 (2000)
Orbital elements of barium stars formed through a wind accretion scenario
J.H. Liu 1,2,
B. Zhang 1,5,
Y.C. Liang 3 and
Q.H. Peng 4,5
1 Department of Physics, Hebei Normal University, Shijiazhuang 050016, P.R. China
2 Department of Physics, Shijianzhuang Teachers' College, Shijiazhuang 050041, P.R. China
3 Beijing Astronomical Observatory, Chinese Academy of Sciences, Beijing 100012, P.R. China
4 Department of Astronomy, Nanjing University, Nanjing 210093, P.R. China
5 Chinese Academy of Sciences - Peking University Joint Beijing Astrophysical Center, Beijing 100871, P.R. China
Received 3 July 2000 / Accepted 11 September 2000
Abstract
Taking the total angular momentum conservation in place of the
tangential momentum conservation, and considering the square and
higher power terms of orbital eccentricity e, the changes of
orbital elements of binaries are recalculated for wind accretion
scenario. These new equations of orbital elements are used to
calculate the properties of barium stars. Our results show that,
during the evolution of a binary system, the system widens as it loses
mass, and the orbital period increases, while orbital eccentricity
remains nearly constant, which can quantitatively explain the observed
(e,logP) properties of normal G, K giants and those of
barium stars. The results reflect the evolution from G, K giant
binaries to barium binaries, namely, the orbits of barium stars have
been modified by the mass-transfer process responsible for their
chemical peculiarities, whereas most of the G, K giant binaries are
probably pre-mass transfer binaries. Moreover, the results showed that
the barium stars with longer orbital period
P![[FORMULA]](img1.gif)
1600 days may be formed by
accreting part of the ejecta from the intrinsic AGB stars through wind
accretion, while those with shorter orbital period may be formed
through dynamically stable late case C mass transfer or common
envelope ejection.
Key words: stars:
late-type 
stars: chemically
peculiar
stars: AGB and
post-AGB
stars:
mass-loss
stars: binaries:
spectroscopic
accretion, accretion disks
Send offprint requests to: Y.C. Liang (lyc@yac.bao.ac.cn)
Contents
- 1. Introduction
- 2. The (e,logP) diagram
- 3. The angular momentum conservation model of wind accretion scenario
- 4. Results and analysis
- 5. Conclusions and discussion
- Acknowledgements
- Appendix: derivation of Eq. (2) and Eq. (3)
- References
© European Southern Observatory (ESO) 2000
Online publication: December 11, 2000
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