The runaway binary LP 400-22 is leaving the Galaxy

KILIC, M.; GIANNINNAS, A.; BROWN, W. R.; HUGH, C. H.; DAHN, C. C.; AGÜEROS, M. A.; HEINKE, C. O.; KENYON, S. J.; PANEI, J. A.; CAMILO, F.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013 vol. 434 p. 3582 - 3589

0035-8711

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.