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تسجيل مستخدم جديدV444 Cyg X-ray and polarimetric variability: Radiative and Coriolis forces shape the wind collision region
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We present results from a study of the eclipsing, colliding-wind binary V444 Cyg that uses a combination of X-ray and optical spectropolarimetric methods to describe the 3-D nature of the shock and wind structure within the system. We have created the most complete X-ray light curve of V444 Cyg to date using 40 ksec of new data from Swift, and 200 ksec of new and archived XMM-Newton observations. In addition, we have characterized the intrinsic, polarimetric phase-dependent behavior of the strongest optical emission lines using data obtained with the University of Wisconsins Half-Wave Spectropolarimeter. We have detected evidence of the Coriolis distortion of the wind-wind collision in the X-ray regime, which manifests itself through asymmetric behavior around the eclipses in the systems X-ray light curves. The large opening angle of the X-ray emitting region, as well as its location (i.e. the WN wind does not collide with the O star, but rather its wind) are evidence of radiative braking/inhibition occurring within the system. Additionally, the polarimetric results show evidence of the cavity the wind-wind collision region carves out of the Wolf-Rayet stars wind.
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The radio emission from the well-studied massive stellar system Cyg OB2 #5 is known to fluctuate with a period of 6.7 years between a low-flux state when the emission is entirely of free-free origin, and a high-flux state when an additional non-therm
al component (of hitherto unknown nature) appears. In this paper, we demonstrate that the radio flux of that non-thermal component is steady on timescales of hours, and that its morphology is arc-like. This shows that the non-thermal emission results from the collision between the strong wind driven by the known contact binary in the system, and that of an unseen companion on a somewhat eccentric orbit with a 6.7-yr period and a 5 to 10 mas semi-major axis. Together with the previously reported wind-collision region located about 0.8 arcsec to the north-east of the contact binary, Cyg OB2 #5 appears to be the only multiple system known so far to harbor two radio-imaged wind-collision regions.
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