The runaway binary LP 400-22 is leaving the Galaxy

We present optical spectroscopy, astrometry, radio and X-ray observations of the runaway binary LP 400-22. We refine the orbital parameters of the system based on our new radial velocity observations. Our parallax data indicate that LP 400-22 is significantly more distant (3σ lower limit of 840 pc) than initially predicted. LP 400-22 has a tangential velocity in excess of 830 km s-1; it is unbound to the Galaxy. Our radio and X-ray observations fail to detect a recycled millisecond pulsar companion, indicating that LP 400-22 is a double white dwarf system. This essentially rules out a supernova runaway ejection mechanism. Based on its orbit, a Galactic Centre origin is also unlikely. However, its orbit intersects the locations of several globular clusters; dynamical interactions between LP 400-22 and other binary stars or a central black hole in a dense cluster could explain the origin of this unusual binary.Fil: Kilic, Mukremin. Oklahoma State University; Estados UnidosFil: Gianninnas, A.. Oklahoma State University; Estados UnidosFil: Brown, Warren R.. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Harris, Hugh C.. US Naval Observatory; Estados UnidosFil: Dahn, Conard C. US Naval Observatory; Estados UnidosFil: Agüeros, M. A.. Columbia University; Estados UnidosFil: Heinke, Craig O.. University of Alberta; CanadáFil: Kenyon, S. J.. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Panei, Jorge Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Camilo, Fernando. Columbia University; Estados Unidos. Arecibo Observatory; Estados Unido