MERLIN observations of the Wolf–Rayet star AS431 (WR147)-a double radio source

Moran, John P.; Davis, R. J.; Bode, M. F.; Taylor, A. R.; Spencer, R. E.; Argue, A. N.; Irwin, M. J.; Shanklin, J. D.

doi:10.1038/340449a0

Cited by 55 publications

(32 citation statements)

References 5 publications

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“…Independent observations with the VLA confirmed this hypothesis (Churchwell et al 1992;Skinner et al 1999). Moran et al (1989) further suggested that WR 147 could have an unseen companion associated with the northern radio source.…”

Section: Introductionmentioning

confidence: 49%

“…The presence of nonthermal radio emission from WR 147 (AS 431) was reported by Caillault et al (1985) and Abbott et al (1986). Later observations with MERLIN at 5 GHz resolved two radio sources (WR 147S and WR 147N) separated by ∼0.6 (Moran et al 1989). The southern thermal source (WR 147S) was coincident with the WR star, and the northern source (WR 147N) was proposed to be responsible for the observed nonthermal emission.…”

Section: Introductionmentioning

confidence: 95%

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High-resolution X-ray imaging of the colliding wind shock in WR 147

Pittard

Stevens

Williams

et al. 2002

A&A

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Abstract. We analyze new high-resolution Chandra X-ray images of the Wolf-Rayet binary system WR147. This system contains a WN8 star with an early-type companion located 0.6 to its north, and is the only known earlytype binary with a separation on the sky large enough for the wind-wind collision between the stars to currently be resolved at X-ray energies. The 5 ksec Chandra HRC-I image provides the first direct evidence for spatially extended X-ray emission in an early-type binary system. The X-ray emission peaks close to the position of the radio bow shock and north of the WN8 star. A deeper X-ray image is needed to accurately determine the degree of spatial extension, to exactly align the X-ray and optical/radio frames, and to determine whether part of the detected X-ray emission arises in the individual stellar winds. Simulated X-ray images of the wind-wind collision have a FWHM consistent with the data, and maximum likelihood fits suggest that a deeper observation may also constrain the inclination and wind momentum ratio of this system. However, as the WR wind dominates the colliding wind X-ray emission it appears unlikely thatṀ OB and v∞ OB can be separately determined from X-ray observations. We also note an inconsistency between numerical and analytical estimates of the X-ray luminosity ratio of the stronger and weaker wind components, and conclude that the analytical results are in error.

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Section: Introductionmentioning

confidence: 49%

Section: Introductionmentioning

confidence: 95%

High-resolution X-ray imaging of the colliding wind shock in WR 147

Pittard

Stevens

Williams

et al. 2002

A&A

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“…The radio emission from wind-wind collisions was calculate by Dougherty et al (2003), using numerical models and including radiation transfer effects and different inclination angles for the orbital plane, to explain the thermal and non-thermal emission detected in several binary systems (Dougherty et al 1996;Dougherty & Williams 2000;Moran et al 1989;Churchwell et al 1992;Williams et al 1997;Niemela et al 1998).…”

Section: Free-free Emission From Shocked Materialsmentioning

confidence: 99%

Millimeter-wave emission during the 2003 low excitation phase ofηCarinae

Abraham

Falceta‐Gonçalves

Dominici

et al. 2005

A&A

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Abstract. In this paper we present observations of η Carinae in the 1.3 mm and 7 mm radio continuum, during the 2003.5 low excitation phase. The expected minimum in the light curves was confirmed at both wavelengths and was probably due to a decrease in the number of UV photons available to ionize the gas surrounding the binary system. At 7 mm a very well defined peak was superimposed on the declining flux density. It presented maximum amplitude in 29 June 2003 and lasted for about 10 days. We show that its origin can be free-free emission from the gas at the shock formed by wind-wind collision, which is also responsible for the observed X-ray emission. Even though the shock strength is strongly enhanced as the two stars in the binary system approach each other, during periastron passage the X-ray emission is strongly absorbed and the 7 mm observations represent the only direct evidence of this event.

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“…In addition, the shock waves in massive binaries are able to accelerate electrons to ultrarelativistic energies, and these electrons can generate nonthermal radio emission via the synchrotron mechanism in the vicinity of the shocks ( Williams et al 1990( Williams et al , 1994Eichler & Usov 1993;White & Becker 1995;Dougherty et al 1996;Jardine et al 1996;Chapman et al 1999;Setia Gunawan et al 2000;Monnier et al 2002a;Pittard et al 2006). For several nearby WR+OB binaries (WR 140,WR 146 and WR 147), the radio sources are spatially resolved, and the radio emission model based on wind-wind collision has been confirmed (Moran et al 1989;Churchwell et al 1992;Niemela et al 1998;Dougherty et al 2000) Dust formation may also occur in the windcollision region ( Usov 1991) and is observed for several massive binaries as an IR excess Marchenko et al 1999;Williams et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Collision of Two Identical Hypersonic Stellar Winds in Binary Systems

Pilyugin

Усов

2007

ApJ

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We investigate the hydrodynamics of two identical hypersonic stellar winds in a binary system. The interaction of these winds manifests itself in the form of two shocks and a contact surface between them. We neglect the binary rotation and assume that the gas flow ahead of the shocks is spherically symmetric. In this case the contact surface that separates the gas emanating from the different stars coincides with the midplane of the binary components. In the shock the gas is heated and flows away nearly along the contact surface. We find the shock shape and the hot gas parameters in the shock layer between the shock and the contact surface.

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MERLIN observations of the Wolf–Rayet star AS431 (WR147)-a double radio source

Cited by 55 publications

References 5 publications

High-resolution X-ray imaging of the colliding wind shock in WR 147

High-resolution X-ray imaging of the colliding wind shock in WR 147

Millimeter-wave emission during the 2003 low excitation phase ofηCarinae

Collision of Two Identical Hypersonic Stellar Winds in Binary Systems

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