Detection of the compressed primary stellar wind in eta Carinae

TL;DR

This study uses HST/STIS spectroscopy over three years to observe partial arcs around eta Carinae, linking them to wind interactions during periastron, confirming simulation predictions.

Contribution

It provides direct observational evidence of wind compression structures in eta Carinae, aligning with 3D hydrodynamical models.

Findings

Detection of three partial arcs in emission lines

Arcs correspond to wind compression shells

Observations match simulation predictions

Abstract

A series of three HST/STIS spectroscopic mappings, spaced approximately one year apart, reveal three partial arcs in [Fe II] and [Ni II] emissions moving outward from eta Carinae. We identify these arcs with the shell-like structures, seen in the 3D hydrodynamical simulations, formed by compression of the primary wind by the secondary wind during periastron passages.