University of Exeter

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Tim Harries
Colliding wind binaries

Introduction

The collision of supersonic stellar winds in a massive binary results in both sspectacular phase-dependent X-ray emission, and complex optical line profile variability. New X-ray observatories, such as XMM-Newton and Chandra, will provide valuable data on the shocked gass, but published models of the optical emission expected from the post-shock flow are very unsophisticated.

Numerical simulations of the optical emission

I have computed the first self-consistent models of H-alpha emission in colliding wind binaries, using the TORUS radiative-transfer code, and a collaboration with Doug Gies (Georgia State) is underway to produce a tailored model for the line-profile variability of the O+O binary Plaskett's star. New phase resolved spectropolarimetric data will be used to investigate both the orbital geometry and the circumstellar electron distribution of a sample of massive binaries.

The picture to the left shows logarithmically scaled electron-scattering optical depth for a generic colliding wind binary. The primary has the stronger wind, and the interaction region is concave with respect to the secondary. The image is linked to an mpeg movie showing how the binary rotates.
This is a simulation of colliding winds using TORUS. Illustrated (clockwise, from top-left) are the intensity image, the intensity + polarization vectors, a greyscaled dynamic spectrum of Halpha, the Halpha spectrum, the velocity image, and finally the polarized intensity image. Note the complex changes in Halpha with phase.

See also Tim Harries' publication list and the Group publications list .

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