Free access article

Issue A&A Volume 376, Number 2, September II 2001 Page(s) 532 - 542 Section Formation, structure and evolution of stars DOI 10.1051/0004-6361:20011006

A&A 376, 532-542 (2001)
DOI: 10.1051/0004-6361:20011006

BeppoSAX observation of the eclipsing dipping X-ray binary X 1658-298

T. Oosterbroek¹, A. N. Parmar¹, L. Sidoli¹, J. J. M. in 't Zand^{2, 3} and J. Heise<sup>3

1</sup>  Astrophysics Division, Space Science Department of ESA, ESTEC, PO Box 299, 2200 AG Noordwijk, The Netherlands
²  Astronomical Institute, Utrecht University, PO Box 80 000, 3508 TA Utrecht, The Netherlands
³  Space Research Organization Netherlands, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands

(Received 8 January 2001 / Accepted 5 July 2001 )

Abstract
Results of a 2000 August 12-13 BeppoSAX observation of the 7.1 hr eclipsing, dipping, bursting, transient, low-mass X-ray binary (LMXRB) X 1658-298 are presented. The spectrum outside of eclipses, dips and bursts can be modeled by the combination of a soft disk-blackbody and a harder Comptonized component with a small amount atom cm^-2) of low-energy absorption. In contrast, an RXTE observation 18 months earlier during the same outburst, measured an absorption of atom cm^-2. Such a change is consistent with a thinning of the accretion disk as the outburst progresses. Structured residuals from the best-fit spectral model are present which are tentatively identified with Ne-K/Fe-L and Fe-K shell emission. The spectral changes during dips are complex and may be modeled by a strong (~ atom cm^-2) increase in absorption of the Comptonized component only, together with reductions in normalizations of both spectral components. This behavior is in contrast to the "complex continuum" model for X-ray dip sources, where the softer blackbody component rapidly suffers strong absorption. It is however, similar to that found during recent XMM-Newton observations of the eclipsing, dipping, LMXRB EXO 0748-676. An updated orbital ephemeris is provided which does not require a quadratic term, in contrast to that of Wachter et al. (2000).

Key words: accretion, accretion disks -- stars: individual: X 1658-298 -- stars: neutron -- X-rays: stars

Offprint request: T. Oosterbroek, toosterb@astro.estec.esa.nl

SIMBAD Objects in preparation

© ESO 2001

What is OpenURL?