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arXiv · 0903.0738

On the origin of high-velocity runaway stars

V. V. Gvaramadze·A. Gualandris·S. Portegies Zwart
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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 Msun 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 $\ga$ 200-400 km/s (typical of pulsars), while 3-4 Msun stars can attain velocities of $\ga$ 300-400 km/s (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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V. V. Gvaramadze, A. Gualandris, S. Portegies Zwart. 2009-03-24. On the origin of high-velocity runaway stars. https://doi.org/10.1111/j.1365-2966.2009.14809.x

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