Vol. 643
7. Stellar structure and evolution

Common-envelope evolution with an asymptotic giant branch star

by C. Sand, S. T. Ohlmann, F. R. N. Schneider, et al. 2020, A&A, 643, A60

Common envelope evolution is an unresolved problem in binary evolution and a key for the formation of double compact objects. Hydrodynamic simulations show that the orbital energy released during spiral-in is not able to eject the complete envelope. The recombination energy of hydrogen and helium has long been proposed to play a crucial role during the ejection process. The authors carried out three-dimensional hydrodynamic simulations to study the common envelope evolution of a 1Msol early-AGB star with companions of different masses. They clearly demonstrate how recombination energy works to eject the complete envelope.