Issue |
A&A
Volume 416, Number 1, March II 2004
|
|
---|---|---|
Page(s) | 311 - 318 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20034266 | |
Published online | 26 February 2004 |
X-ray spectral evolution of SAX J1747.0-2853 during outburst activity and confirmation of its transient nature
1
Faculty of Sciences, P. J. Safarik University, Moyzesova 16, 040 01 Kosice, Slovak Republic
2
SRON National Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
3
Astronomical Institute, Utrecht University, PO Box 80000, 3508 TA Utrecht, The Netherlands
4
Istituto di Astrofisica Spaziale (CNR), Area Ricerca Roma Tor Vergata, via del Fosso del Cavaliere, 00133 Roma, Italy
5
NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA
6
Dept. of Astronomy, University of Maryland, College Park, MD 20742, USA
7
Dept. of Physics and Astronomy, University of Southampton, Hampshire SO17 1BJ, UK
Corresponding author: N. Werner, werner@ta3.sk
Received:
2
September
2003
Accepted:
29
November
2003
SAX J1747.0-2853 is an X-ray transient which exhibited X-ray
outbursts yearly between 1998 and 2001, and most probably also in
1976. The outburst of 2000 was the longest and brightest. We have
analyzed X-ray data sets that focus on the 2000 outburst and were
obtained with BeppoSAX, XMM-Newton and RXTE. The data cover unabsorbed
2–10 keV fluxes between 0.1 and
erg s-1 cm-2. The equivalent luminosity
range is
to
erg s-1. The
0.3–10 keV spectrum is well described by a
combination of a multi-temperature disk blackbody, a hot
Comptonization component and a narrow Fe–K emission
line at 6.5 to 6.8 keV with an equivalent width of up to 285 eV. The
hydrogen column density in the line of sight is
cm-2. The most conspicuous spectral
changes in this model are represented by variations of the temperature
and radius of the inner edge of the accretion disk, and a jump of the
equivalent width of the Fe–K line in one observation. Furthermore, 45
type-I X-ray bursts were unambiguously detected between 1998 and 2001
which all occurred during or close to outbursts. We derive a distance
of
kpc which is consistent with previous
determinations. Our failure to detect bursts for prolonged periods
outside outbursts provides indirect evidence that the source
returns to quiescence between outbursts and is a true transient.
Key words: accretion, accretion disks / X-rays: binaries / X-rays: bursts / X-rays: individual: SAX J1747.0-2853
© ESO, 2004
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