Astron. Astrophys. 321, 207-212 (1997)

The formation of black-holes in low-mass X-ray binaries

Simon F. Portegies Zwart ¹, Frank Verbunt ¹ and Ene Ergma <sup>2

1</sup> Astronomical Institute, Utrecht, Postbus 80000, 3508 TA Utrecht, The Netherlands
² Tartu University, Physics Department, Ülikooli 18, EE2400 Tartu, Estonia

Received 24 April 1996 / Accepted 12 September 1996

Abstract

We calculate the formation rates of low-mass X-ray binaries with a black hole. Both a semi-analytic and a more detailed model predict formation rates two orders of magnitude lower than derived from the observations. Solution of this conundrum requires either that stars with masses less than 20  can evolve into a black hole, or that stellar wind from a member of a binary is accompanied by a much larger loss of angular momentum than hitherto assumed.

Key words: binaries: close stars: evolution stars: neutron X-rays: stars

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Contents

• 1. Introduction
• 2. Semi-analytic approach
• 3. Detailed model
• 4. Galactic formation rates
• 5. Discussion
• 6. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998
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