Accretion onto the Companion of Eta Carinae During the Spectroscopic Event: III. the He II 4686 Line

Abstract

We continue to explore the accretion model of the massive binary system eta Carinae by studying the anomalously high He II 4686 line. The line appears just before periastron and disappears immediately thereafter. Based on the He II 4686 line emission from O-stars and their modeling in the literature, we postulate that the He II 4686 line comes from the acceleration zone of the secondary stellar wind. We attribute the large increase in the line intensity to a slight increase in the density of the secondary stellar wind in its acceleration zone. The increase in density could be due to the ionization and subsequent deceleration of the wind by the enhanced X-ray emission arising from the shocked secondary wind further downstream or to accretion of the primary stellar wind. Accretion around the secondary equatorial plane gives rise to collimation of the secondary wind, which increases its density, hence enhancing the He II 4686 emission line. In contrast with previous explanations, the presently proposed model does not require a prohibitively high X-ray flux to directly photoionize the He.

ApJ, in press

Cited by in corpus (9)

• A multispectral view of the periodic events in eta Carinae
• Possible Implications of Mass Accretion in Eta Carinae
• Eta Carinae's 2014.6 Spectroscopic Event: Clues to the Long-term Recovery from its Great Eruption
• The Source of the Helium Visible Lines in Eta Carinae
• The Orientation of the Eta Carinae Binary System
• Modelling the Radio Light Curve of Eta Carinae
• Accretion onto the Companion of Eta Carinae During the Spectroscopic Event. V. the Infrared Decline
• A high-velocity transient outflow in Eta Carinae
• The X-ray properties of Eta Carinae during its 2020 X-ray minimum