EDP Sciences
Free access
Issue
A&A
Volume 398, Number 3, February II 2003
Page(s) L25 - L28
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20021767


A&A 398, L25-L28 (2003)
DOI: 10.1051/0004-6361:20021767

Letter

The origin of Scorpius X-1

I. F. Mirabel1, 2 and I. Rodrigues1

1  Service d'Astrophysique / CEA-Saclay, 91191 Gif-sur-Yvette, France
2  Instituto de Astronomía y Física del Espacio/Conicet, Argentina

(Received 17 October 2002/Accepted 1 December 2002)

Abstract
We have used multi-wavelength observations of high precision to derive the space velocity and compute the orbit around the Galactic Centre of the prototype X-ray binary Scorpius X-1. An origin in the local spiral arm of the Milky Way is ruled out. The galactocentric kinematics of Scorpius X-1 is similar to that of the most ancient stars and globular clusters of the inner Galactic halo. Most probably, this low-mass X-ray binary was formed by a close encounter in a globular cluster. However, it cannot be ruled out that a natal supernova explosion launched Scorpius X-1 into an orbit like this from a birth place in the galactic bulge. In any case, the Galactocentric orbit indicates that Scorpius X-1 was formed more than 30 Myrs ago.


Key words: stars: individual: Scorpius X-1 -- X-rays: binaries -- astrometry

Offprint request: I. F. Mirabel, fmirabel@cea.fr

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