On the origin of high-velocity runaway stars |
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| Authors: | Vasilii V Gvaramadze Alessia Gualandris Simon Portegies Zwart |
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| Institution: | Sternberg Astronomical Institute, Moscow State University, Universitetskij Pr. 13, Moscow 119992, Russia;Center for Computational Relativity and Gravitation, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester NY 14623, USA;Astronomical Institute 'Anton Pannekoek' and Section Computational Science, Amsterdam University, Kruislaan 403, 1098 SJ Amsterdam, the Netherlands |
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| Abstract: | We explore the hypothesis that some high-velocity runaway stars attain their peculiar velocities in the course of exchange encounters between hard massive binaries and a very massive star (either an ordinary 50–100 M⊙ star or a more massive one, formed through runaway mergers of ordinary stars in the core of a young massive star cluster). In this process, one of the binary components becomes gravitationally bound to the very massive star, while the second one is ejected, sometimes with a high speed. We performed three-body scattering experiments and found that early B-type stars (the progenitors of the majority of neutron stars) can be ejected with velocities of ?200–400 km s?1 (typical of pulsars), while 3–4 M⊙ stars can attain velocities of ?300–400 km s?1 (typical of the bound population of halo late B-type stars). We also found that the ejected stars can occasionally attain velocities exceeding the Milky Ways's escape velocity. |
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| Keywords: | stellar dynamics methods: N-body simulations binaries: general stars: individual: HD 271791 stars: neutron |
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