Integral-field spectroscopy of the post-red supergiant IRC+10420: Evidence for an axisymmetric wind

We present NAOMI/OASIS adaptive-optics-assisted integral-field spectroscopy of the transitional massive hyper-giant IRC + 10420, an extreme mass-losing star apparently in the process of evolving from a red supergiant toward the Wolf-Rayet phase. To investigate the present-day mass-loss geometry of the star, we study the appearance of the line emission from the inner wind as viewed when reflected off the surrounding nebula. We find that, contrary to previous work, there is strong evidence for wind axisymmetry, based on the equivalent width and velocity variations of H alpha and Fe (II) lambda 6516. We attribute this behavior to the appearance of the complex line profiles when viewed from different angles. We also speculate that the Ti (II) emission originates in the outer nebula in a region analogous to the strontium filament of eta Carinae, based on the morphology of the line emission. Finally, we suggest that the present-day axisymmetric wind of IRC + 10420, combined with its continued blueward evolution, is evidence that the star is evolving toward the B[e] supergiant phase.