White-dwarf red-giant mergers, early-type R stars, J stars and lithium

Xianfei Zhang, C. Simon Jeffery

Early-type R stars and J stars are a special type of carbon star, having enhanced nitrogen ($[N/Fe]\approx 0.5$), lithium, a low \iso{12}{C}/\iso{13}{C} ratio ($<15$) and no s-…