EDP Sciences
Free access
Volume 409, Number 2, October II 2003
Page(s) 659 - 663
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20031042

A&A 409, 659-663 (2003)
DOI: 10.1051/0004-6361:20031042

A peculiar type-I X-ray burst from GRS 1747-312

J. J. M. in 't Zand1, 2, T. E. Strohmayer3, C. B. Markwardt3, 4 and J. Swank3

1  SRON National Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
2  Astronomical Institute, Utrecht University, PO Box 80000, 3508 TA Utrecht, The Netherlands
3  NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA
4  Dept. of Astronomy, University of Maryland, College Park, MD 20742, USA

(Received 19 May 2003 / Accepted 3 July 2003 )

We report the serendipitous detection with the Rossi X-ray Timing Explorer of a long and peculiar X-ray burst whose position is consistent with one known X-ray burster (GRS 1747-312) and which occurred when that source was otherwise quiescent. The peculiar feature concerns a strong radius expansion of the neutron star photosphere, which occurred not within a few seconds from the start of the burst, as is standard in radius-expansion bursts, but 20 s later. This suggests that two different layers of the neutron star may have undergone thermonuclear runaways: a hydrogen-rich and a hydrogen-poor layer. The reason for the delay may be related to the source being otherwise quiescent.

Key words: accretion, accretion disks -- globular clusters: individual: Terzan 6 -- X-rays: binaries -- X-rays: bursts -- X-rays: individuals: GRS 1747-312

Offprint request: J. J. M. in 't Zand, jeanz@sron.nl

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