Fluorine in R Coronae Borealis Stars

Abstract

Neutral fluorine (F I) lines are identified in the optical spectra of several R Coronae Borealis stars (RCBs) at maximum light. These lines provide the first measurement of the fluorine abundance in these stars. Fluorine is enriched in some RCBs by factors of 800 to 8000 relative to its likely initial abundance. The overabundances of fluorine are evidence for the synthesis of fluorine. These results are discussed in the light of the scenario that RCBs are formed by accretion of an He white dwarf by a C-O white dwarf. Sakurai's object (V4334 Sgr), a final He-shell flash product, shows no detectable F I lines.

25 pages, 7 figures, accepted to ApJ

References in corpus (2)

• R Coronae Borealis at the 2003 Light Minimum
• Abundance analysis of cool extreme helium star: LSS 3378

Cited by in corpus (3)

• Post-merger evolution of carbon-oxygen + helium white dwarf binaries and the origin of R Coronae Borealis and extreme helium stars
• Discovery of Bright Galactic R Coronae Borealis and DY Persei Variables: Rare Gems Mined from ACVS
• On the binary helium star DY Centauri: Chemical composition and evolutionary state