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Abundances of neutron-capture elements in the Hot Extreme-Helium Stars V1920 Cygni and HD 124448

Gajendra Pandey·David L. Lambert·N. Kameswara Rao·C. Simon Jeffery
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Abstract

Analysis of HST STIS ultraviolet spectra of two hot extreme helium stars (EHes): V1920 Cyg and HD 124448 provide the first measurements of abundances of neutron-capture elements for EHes. Although the two stars have similar abundances for elements up through the iron-group, they differ strikingly in their abundances of heavier elements: V1920 Cyg is enriched by a factor of 30 in light neutron-capture elements (Y/Fe, Zr/Fe) relative to HD 124448. These differences in abundances of neutron-capture elements among EHes mirrors that exhibited by the RCrB stars, and is evidence supporting the view that there is an evolutionary connection between these two groups of hydrogen-deficient stars. Also, the abundances of Y and Zr in V1920 Cyg provide evidence that at least one EHe star went through a s-process synthesis episode in its earlier evolution.

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Gajendra Pandey, David L. Lambert, N. Kameswara Rao, C. Simon Jeffery. 2004-01-14. Abundances of neutron-capture elements in the Hot Extreme-Helium Stars V1920 Cygni and HD 124448. https://doi.org/10.1086/382684

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