Astron. Astrophys. 347, 891-896 (1999)

Broad-band X-ray measurements of GS 1826-238

J.J.M. in 't Zand ¹, J. Heise ¹, E. Kuulkers ^1,2, A. Bazzano ³, M. Cocchi ³ and P. Ubertini <sup>3

1</sup> Space Research Organization Netherlands, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
² Astronomical Institute, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
³ Istituto di Astrofisica Spaziale (CNR), Area Ricerca Roma Tor Vergata, Via del Fosso del Cavaliere, I-00133 Roma, Italy

Received 12 February 1999 / Accepted 6 April 1999

Abstract

The broad band X-ray spectrum of the low-mass X-ray binary (LMXB) GS 1826-238 was measured with the narrow-field instruments on BeppoSAX on April 6 and 7, 1997. The spectrum is consistent with the Comptonization of a 0.6 keV thermal spectrum by a hot cloud of temperature equivalent  keV. During the observation two type I X-ray bursts were detected. From the bursts an upper limit to the distance could be derived of 8 kpc. Combined with an elsewhere determined lower limit of 4 kpc this implies a persistent X-ray luminosity between and  erg s^-1 which is fairly typical for a LMXB X-ray burster. The accurate determination of the energetics of the two bursts and the persistent emission confirm results with the Wide Field Cameras on BeppoSAX in a narrower bandpass (Ubertini et al. 1999). Comparison with independent X-ray measurements taken at other times indicates that GS 1826-238 since its turn-on in 1988 is a rather stable accretor, which is in line with the strong regularity of type I X-ray bursts.

Key words: stars: individual: GS 1826-238 stars: neutron X-rays: bursts X-rays: stars

Send offprint requests to: J.J.M. in 't Zand (jeanz@sron.nl)

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Contents

• 1. Introduction
• 2. Observations
• 3. The persistent emission
• 4. The burst emission
• 5. Discussion
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: June 6, 1999
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