Free access article

Issue A&A Volume 431, Number 2, February IV 2005 Page(s) 647 - 658 Section Stellar structure and evolution DOI 10.1051/0004-6361:20041777

A&A 431, 647-658 (2005)
DOI: 10.1051/0004-6361:20041777

Creating ultra-compact binaries in globular clusters through stable mass transfer

M. V. van der Sluys, F. Verbunt and O. R. Pols

Astronomical Institute, Princetonplein 5, 3584 CC Utrecht, The Netherlands
    e-mail: [sluys;verbunt;pols]@astro.uu.nl

(Received 2 August 2004 / Accepted 23 October 2004)

Abstract
A binary in which a slightly evolved star starts mass transfer to a neutron star can evolve towards ultra-short orbital periods under the influence of magnetic braking. This is called magnetic capture. We investigate in detail for which initial orbital periods and initial donor masses binaries evolve to periods less than 30-40 min within the Hubble time. We show that only small ranges of initial periods and masses lead to ultra-short periods, and that for those only a small time interval is spent at ultra-short periods. Consequently, only a very small fraction of any population of X-ray binaries is expected to be observed at ultra-short period at any time. If 2 to 6 of the 13 bright X-ray sources in globular clusters have an ultra-short period, as suggested by recent observations, their formation cannot be explained by the magnetic capture model.

Key words: stars: binaries: close -- stars: evolution -- Galaxy: globular clusters: general -- X-rays: binaries

SIMBAD Objects

© ESO 2005

What is OpenURL?