3-D SPH simulations of colliding winds in eta Carinae

TL;DR

This paper uses 3D SPH simulations to model the colliding winds in eta Carinae, revealing the structure of the wind cavity and matching observed X-ray light curves.

Contribution

It introduces a 3D SPH simulation approach to study wind interactions in eta Carinae, providing detailed cavity structures and phase-dependent behavior.

Findings

The secondary wind creates a spiral cavity in the primary wind.

The cavity's shape varies with orbital phase, being thin at periastron.

Simulated X-ray light curve matches observations at specific viewing angles.

Abstract

We study colliding winds in the superluminous binary eta Carinae by performing three-dimensional, Smoothed Particle Hydrodynamics (SPH) simulations. For simplicity, we assume both winds to be isothermal. We also assume that wind particles coast without any net external forces. We find that the lower density, faster wind from the secondary carves out a spiral cavity in the higher density, slower wind from the primary. Because of the phase-dependent orbital motion, the cavity is very thin on the periastron side, whereas it occupies a large volume on the apastron side. The model X-ray light curve using the simulated density structure fits very well with the observed light curve for a viewing angle of i=54 degrees and phi=36 degrees, where i is the inclination angle and phi is the azimuth from apastron.