Cygnus X-3 with ISO: investigating the wind |
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| Authors: | R N Ogley † S J Bell Burnell R P Fender |
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| Institution: | Department of Physics and Astronomy, The Open University, Milton Keynes MK7 6AA;Astronomical Institute 'Anton Pannekoek' and Center for High Energy Astrophysics, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, the Netherlands |
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| Abstract: | We have observed the energetic binary Cygnus X-3 in both quiescent and flaring states between 4 and 16 μm using the ISO satellite. We find that the quiescent source shows the thermal free–free spectrum typical of a hot, fast stellar wind, such as from a massive helium star. The quiescent mass-loss rate arising from a spherically symmetric, non-accelerating wind is found to be in the range (0.4–2.9)×10?4 M⊙ yr?1, consistent with other infrared and radio observations, but considerably larger than the 10?5 M⊙ yr?1 deduced from both the orbital change and the X-ray column density. There is rapid, large-amplitude flaring at 4.5 and 11.5 μm at the same time as enhanced radio and X-ray activity, with the infrared spectrum apparently becoming flatter in the flaring state. We believe that non-thermal processes are operating, perhaps along with enhanced thermal emission. |
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| Keywords: | binaries: close stars: individual: Cyg X-3 stars: mass-loss stars: Wolf–Rayet infrared: stars X-rays: stars |
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