Orbit upright=1.6|left|thumb|alt=η Carinae B orbits in large ellipse, and η Carinae A in a smaller elliptical orbit.|Eta Carinae orbit The binary nature of η Carinae is clearly established, although the components have not been directly observed and cannot even be clearly resolved spectroscopically due to scattering and re-excitation in the surrounding nebulosity. Periodic photometric and spectroscopic variations prompted the search for a companion, and modelling of the colliding winds and partial "eclipses" of some spectroscopic features have constrained the possible orbits.
orbit upright=16|left|thumb|alt=η carinae b orbits in large ellipse and η carinae a in a smaller elliptical orbit|eta carinae orbit the binary nature of η carinae is clearly established although the components have not been directly observed and cannot even be clearly resolved spectroscopically due to scattering and re-excitation in the surrounding nebulosity periodic photometric and spectroscopic variations prompted the search for a companion and modelling of the colliding winds and partial "eclipses" of some spectroscopic features have constrained the possible orbits