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Multiwavelength observations revealing the outbursts of the soft X-ray transients XTE J1859+226 and XTE J1118+480

S. Chaty·C. A. Haswell·R. I. Hynes·C. R. Shrader·W. Cui
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Abstract

We report multiwavelength observations of the two soft X-ray transients (SXTs) XTE J1859+226 and XTE J1118+480, which we observed with HST, RXTE and UKIRT. The two sources exhibited very different behaviour. XTE J1859+226 showed a thermal-viscous disc instability outburst modified by irradiation. XTE J1118+480, which we also observed with EUVE since it is located at a very high galactic latitude and suffers from very low extinction, is much more unusual. It exhibits i) a low X-ray to optical flux ratio and ii) a strong non-thermal contribution throughout the spectrum, which is likely to be due to synchrotron emission. We concentrate here on their evolution in the course of their outbursts.

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S. Chaty, C. A. Haswell, R. I. Hynes, C. R. Shrader, W. Cui. 2001-08-15. Multiwavelength observations revealing the outbursts of the soft X-ray transients XTE J1859+226 and XTE J1118+480. https://arxiv.org/abs/astro-ph/0108242

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