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Ultra-compact (X-ray) binaries

G. Nelemans·P. G. Jonker
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Abstract

A short review of ultra-compact binaries, focused on ultra-compact X-ray binaries, is followed by a discussion of recent results of our VLT campaign to obtain optical spectra of (candidate) ultra-compact X-ray binaries. We find evidence for carbon/oxygen as well as helium/nitrogen discs and no evidence for (traces) of hydrogen. This suggests that the donors in the observed systems are white dwarfs. However, we also find large differences between the two C/O discs of which we have good spectra, which highlights the need for a better understanding of the optical spectra.

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G. Nelemans, P. G. Jonker. 2006-05-30. Ultra-compact (X-ray) binaries. https://doi.org/10.1016/j.newar.2010.09.021

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