A STELLAR ENDGAME - THE BORN-AGAIN SAKURAI OBJECT

The surface chemical composition of this remarkable star shows that it is hydrogen-deficient, carbon-rich and enriched in the light s-proces s elements. Spectra taken in May and October 1996 indicate a decrease in the surface hydrogen abundance by 0.7 dex in five months along with an increase in the abundances of Li, Sr, Y and Zr. The abundance chan ges are in agreement with the hypothesis of the star being a rapidly e volving ''born-again'' AGB star experiencing a final He-shell flash, s imilar to FG Sge. The C-12/C-13 ratio in October is very low, also sug gesting hydrogen ingestion. By chemical composi tion, Sakurai's object resembles the R Coronae Borealis (R CrB) stars.