3D modelling of the colliding winds in η Carinae - evidence for radiative inhibition

Abstract

The X-ray emission from the supermassive star Car is simulated using a 3D model of the wind-wind collision. In the model the intrinsic X-ray emission is spatially extended and energy dependent. Absorption due to the unshocked stellar winds and the cooled post-shock material from the primary LBV star is calculated as the intrinsic emission is ray traced along multiple sightlines through the 3D spiral structure of the circumstellar environment. The observable emission is then compared to available X-ray data, including the light curve observed by the Rossi X-ray Timing Explorer (RXTE) and spectra observed by XMM-Newton. The orientation and eccentricity of the orbit are explored, as are the wind parameters of the stars and the nature and physics of their close approach. Our modelling supports a viewing angle with an inclination of 42 , consistent with the polar axis of the Homunculus nebula, and the projection of the observer's line of sight on to the orbital plane has an angle of 0 -30 in the prograde direction on the apastron side of the semimajor axis.