Prediction for the He I Λ10830å Absorption Wing in the Coming Event of Eta Carinae

We propose an explanation to the appearance of a wide blue absorption wing in the He I λ10830Å P Cygni profile of the massive binary star η Car several months before periastron. We assume that the mixing regions of the two wind is accelerated by the secondary’s wind to ∼ 1800 km s, and is responsible for the absorption. 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 orientation we use can account for the appearance and evolution of the wide blue wing. (2)We predict that the Doppler shift (the edge of the absorption profile) will reach a maximum 5 − 15 day before periastron passage. We encourage a nightly observation of η Car in this line to start December 28, 2008, and continue to several days after periastron. Subject headings: (stars:) binaries: general−stars: mass loss−stars: winds, outflows−stars: individual (η Car)