The atmosphere of the extremely high-velocity ( 530 - 920 { km s ^ { -1 } } ) early B-type star HD 271791 is enriched in \alpha -process elements , which suggests that this star is a former secondary component of a massive tight binary system and that its surface was polluted by the nucleosynthetic products after the primary star exploded in a supernova .
It was proposed that the ( asymmetric ) supernova explosion unbind the system and that the secondary star ( HD 271791 ) was released at its orbital velocity in the direction of Galactic rotation .
In this Letter , we show that to explain the Galactic rest-frame velocity of HD 271791 within the framework of the binary-supernova scenario , the stellar remnant of the supernova explosion ( a \la 10 M _ { \odot } black hole ) should receive an unrealistically large kick velocity of \geq 750 - 1200 { km s ^ { -1 } } .
We therefore consider the binary-supernova scenario as highly unlikely and instead propose that HD 271791 attained its peculiar velocity in the course of a strong dynamical three- or four-body encounter in the dense core of the parent star cluster .
Our proposal implies that by the moment of encounter HD 271791 was a member of a massive post-supernova binary .