N II 5668-5712, a New Class of Spectral Features in Eta Carinae

TL;DR

This paper identifies a new class of spectral features, N II 5668-5712 lines, in Eta Carinae's spectrum, revealing their origin in undisturbed primary wind regions and their dependence on the secondary star's position.

Contribution

It introduces the N II 5668-5712 emission and absorption lines as a new spectral feature class in Eta Carinae, clarifying their origin and implications for existing models.

Findings

N II lines originate in undisturbed primary wind zones.

N II lines depend on the secondary star's location.

These lines challenge models placing He I lines in the secondary wind or accretion disk.

Abstract

We report on the N II 5668-5712 emission and absorption lines in the spectrum of Eta Carinae. Spectral lines of the stellar wind regions can be classified into four physically distinct categories: 1) low-excitation emission such as H I and Fe II, 2) higher excitation He I features, 3) the N II lines discussed in this paper, and 4) He II emission. These categories have different combinations of radial velocity behavior, excitation processes, and dependences on the secondary star. The N II lines are the only known features that originate in "normal" undisturbed zones of the primary wind but depend primarily on the location of the hot secondary star. N II probably excludes some proposed models, such as those where He I lines originate in the secondary star's wind or in an accretion disk.