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

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.

arXiv comment4 pages (embedded figure and table), accepted for publication in ApJ Letters

References in corpus (2)

• Abundance analyses of cool extreme helium stars
• A High-resolution Spectrum of the R CrB Star V2552 Ophiuchi

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