Secular contraction in extreme helium stars and the future of V4334 Sgr |
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Authors: | C.S. Jeffery R.L.C. Starling P.W. Hill D. Pollacco |
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Affiliation: | (1) Armagh Observatory, College Hill, Armagh, BT61 9DG, UK;(2) Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK;(3) School of Physics and Astronomy, University of St. Andrews, North Haugh, St Andrews, Fife, KY16 9SS;(4) Department of Pure and Applied Physics, Queen's University Belfast, Belfast, BT7 1NN, UK |
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Abstract: | Speculative connections have been made between Sakurai's Object andother hydrogen-deficient stars, principally the RCB stars and [WC]central stars of planetary nebulae. RCBs have also been postulated as the precursors of extreme helium stars (EHes). The question arises to whether Sakurai's Object will evolve down the [WC]-PG1159 evolution track, or the RCB-EHe-HesdO track. From a number of IUE observations, we have measured thesecular contraction rates and pulsation masses of several EHes. These are inconsistent with the predicted contraction rates for helium-shell burning giants produced by a final helium-shell flash (the [WC]-PG1159 track). Although there may be some similarities between Sakurai's Object and some RCBs, if the RCB-EHe conection is valid then these must be superficial rather than structural. |
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Keywords: | Stars: chemically peculiar Stars: evolution Stars:pulsation Stars: fundamental parameters |
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