English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The origin of R Coronae Borealis stars has been elusive for over 200 years.Currently, two theories for their formation have been presented. These are theFinal Flash scenario, in which a dying asymptotic giant branch (AGB) starthrows off its atmosphere to reveal the hydrogen poor, heavily processedmaterial underneath, and the double degenerate scenario, in which two whitedwarfs merge to produce a new star with renewed vigour. Some theories predictthat the temperatures reached during the latter scenario would destroy anylithium originally present in the white dwarfs. The observed lithium content ofsome R Coronae Borealis stars, therefore, is often interpreted as an indicationthat the Final Flash scenario best describes their formation. In this paper, itis shown that lithium production can, indeed, occur in the merging of a heliumwhite dwarf with a carbon-oxygen white dwarf if their chemical composition,particularly that of 3He, is fully considered. The production mechanism isdescribed in detail, and the sensitivity of lithium production to the mergerenvironment is investigated. Nucleosynthesis post-processing calculations ofsmoothed-particle hydrodynamics (SPH) tracer particles are performed to showthat any lithium produced in these environments will be concentrated towardsthe cloud of material surrounding the R CrB star. Measurements of the lithiumcontent of these clouds would, therefore, provide a valuable insight into theformation mechanism of R CrB stars.

Lithium production in the merging of white dwarf stars