Prediction for the He I 10830A Absorption Wing in the Coming Event of Eta Carinae

TL;DR

This paper explains the appearance of a wide blue absorption wing in Eta Carinae's He I 10830A profile by modeling colliding stellar winds, predicting its evolution and maximum Doppler shift timing before periastron.

Contribution

It introduces a toy-model linking wind collision regions to spectral features, providing a new explanation for observed absorption wing behavior in Eta Carinae.

Findings

Maximum outflow velocity of ~2300 km/s in the absorbing material.

The model accounts for the appearance and evolution of the blue wing.

Doppler shift peaks 0-3 weeks before periastron.

Abstract

We propose an explanation to the puzzling appearance of a wide blue absorption wing in the He I 10830A P-Cygni profile of the massive binary star Eta Carinae several months before periastron passage. Our basic assumption is that the colliding winds region is responsible for the blue wing absorption. By fitting observations, we find that the maximum outflow velocity of this absorbing material is ~2300 km/s. We also assume that the secondary star is toward the observer at periastron passage. With a toy-model we achieve two significant results. (1) We show that the semimajor axis orientation we use can account for the appearance and evolution of the wide blue wing under our basic assumption. (2) We predict that the Doppler shift (the edge of the absorption profile) will reach a maximum 0-3 weeks before periastron passage, and not necessarily exactly at periastron passage or after periastron passage.