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Astron. Astrophys. 332, 651-660 (1998)


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Abundance similarities between the R CrB star V854 Cen and the born-again Sakurai's object

Martin Asplund * 1, Bengt Gustafsson 1, N. Kameswara Rao 2 and David L. Lambert ** 3

1 Astronomiska Observatoriet, Box 515, S-751 20 Uppsala, Sweden
2 Indian Institute of Astrophysics, Bangalore 560 034, India
3 Department of Astronomy, University of Texas, Austin, TX 78712, USA

Received 1 July 1997 / Accepted 15 December 1997

Abstract

The elemental abundances of the mildly hydrogen-deficient R Coronae Borealis (R CrB) star V854 Cen have been estimated. The R CrB stars have been divided into majority and minority classes judging by their abundance patterns. Class assignment has previously been unambiguous but V854 Cen has traits of both the minority and majority class. Neither V854 Cen nor the three obvious minority members show any clear abundance signatures of having been affected by e.g. dust-gas separation as often observed in post-AGB stars. By chemical composition, V854 Cen closely resembles Sakurai's object, which has probably recently experienced a final He-shell flash. Therefore V854 Cen and Sakurai's object may share the same evolutionary background, which would add support for the final-flash scenario as a viable origin of the R CrB stars. Most of the few differences in abundance ratios between the stars could if so be attributed to milder H-ingestion in connection with the final He-shell flash of V854 Cen. The identification of either the majority or the minority group, if any, as final flash objects, remain uncertain, however, due to the unclear membership status of V854 Cen.

Key words: stars: individual: V854 Cen – stars: variables: R Coronae Borealis – stars: abundances – stars: AGB and post-AGB – stars: evolution – stars: individual: Sakurai's object

* Present address: NORDITA, Blegdamsvej 17, DK-2100 Copenhagen O, Denmark
** Visiting Astronomer at Cerro Tololo Inter-American Observatory (CTIO), which is operated by the Association of Universities for Research in Astronomy Inc., under contract with the National Science Foundation

Send offprint requests to: M. Asplund (martin@nordita.dk)

© European Southern Observatory (ESO) 1998

Online publication: March 23, 1998
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