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Surface Compositions of R Coronae Borealis Stars and Extreme Helium Stars - Some Connections

N. Kameswara Rao
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Abstract

Abundances of R Coronae Borealis stars (RCBs) and Extreme Helium stars (EHes) are discussed. Recent estimates of the $s$-process elements in hot extreme helium stars show enhancements of lighter $s$-process elements (Y, Zr) relative to heavier $s$-process elements, a characteristic shared by RCB stars. It also suggests that atleast some EHe stars went through an episode of $s$-process element synthesis in their earlier evolution. A majority of RCB stars show a high $^{12}$C/$^{13}$C ratio in their atmospheres. A recent analysis of the spectrum of minority RCB star V CrA, however, shows a lower value between 4 $-$ 10. The implications of these results are discussed.

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N. Kameswara Rao. 2004-10-27. Surface Compositions of R Coronae Borealis Stars and Extreme Helium Stars - Some Connections. https://arxiv.org/abs/astro-ph/0410648

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