Rxte discovery of coherent millisecond pulsations during an x-ray burst from ks 1731-260
Dec, 199615 pages
Published in:
- Astrophys.J.Lett. 479 (1997) L137
e-Print:
- astro-ph/9612221 [astro-ph]
DOI:
Report number:
- CSR-96-49
View in:
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Abstract: (arXiv)
A highly coherent 523.92+-0.05 Hz periodic X-ray signal has been observed during a type I X-ray burst from the low-mass X-ray binary system KS 1731-260 with the PCA on RXTE. The spectral evolution of the burst indicates photospheric-radius expansion and contraction. The 524 Hz signal occurred at the end of the contraction phase, lasted for ~2 s, was highly coherent (Q >~ 900), and had a pulse fraction (ratio of sinusoidal amplitude to mean count rate) of 6.2+-0.6%. KS 1731-260 is one of only three systems that have exhibited high-coherence millisecond oscillations during X-ray bursts and the first reported where the pulsations are associated with photospheric contraction. These coherent signals may be interpreted as a direct indication of the neutron star spin.References(20)
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