Volume 498, Number 2, May I 2009
|Page(s)||489 - 500|
|Section||Stellar structure and evolution|
|Published online||18 February 2009|
Spectroscopic binaries among Hipparcos M giants*
III. The eccentricity – period diagram and mass-transfer signatures
Institut d'Astronomie et d'Astrophysique, Université Libre de Bruxelles, CP. 226, Boulevard du Triomphe, 1050 Bruxelles, Belgium e-mail: email@example.com
Accepted: 20 December 2008
Context. This paper is the third one in a series devoted to studying the properties of binaries involving M giants.
Aims. We use a new set of orbits to construct the first (e - log P) diagram of an extensive sample of M giant binaries, to obtain their mass-function distribution, and to derive evolutionary constraints for this class of binaries and related systems.
Methods. The orbital properties of binaries involving M giants were analysed and compared with those of related families of binaries (K giants, post-AGB stars, barium stars, Tc-poor S stars).
Results. The orbital elements of post-AGB stars and M giants are not very different, which may indicate that, for the considered sample of post-AGB binaries, the post-AGB star left the AGB at quite an early stage (M4 or so). Neither are the orbital elements of post-mass-transfer binaries like barium stars very different from those of M giants, suggesting that the mass transfer did not alter the orbital elements much, contrary to current belief. Finally, we show that binary systems with e < 0.4 log P - 1 (with periods expressed in days) are predominantly post-mass-transfer systems, because (i) the vast majority of barium and S systems match this condition; and (ii) these systems have companion masses peaking around 0.6 , as expected for white dwarfs. The latter property has been shown to hold as well for open-cluster binaries involving K giants, for which a lower bound on the companion mass may easily be set.
Key words: stars: binaries: spectroscopic / stars: AGB and post-AGB / stars: late-type / stars: binaries: symbiotic
© ESO, 2009
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.