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.

arXiv commentApJ, in press

References in corpus (19)

• Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions
• In Hot Pursuit of the Hidden Companion of Eta Carinae: An X-ray Determination of the Wind Parameters
• Eta Carinae: Binarity Confirmed
• Dissecting the Homunculus nebula around Eta Carinae with spatially resolved near-infrared spectroscopy
• The Binarity of Eta Carinae Revealed from Photoionization Modeling of the Spectral Variability of the Weigelt Blobs B and D
• The 2003 Shell Event in eta Carinae
• On the He II Emission In Eta Carinae and the Origin of Its Spectroscopic Events
• The Purple Haze of Eta Carinae: Binary-Induced Variability?
• Detection of He II 4686 in eta Carinae
• The Departure of Eta Carinae from Axisymmetry and the Binary Hypothesis
• Detection of a Hot Binary Companion of $\eta$ Carinae
• The CHANDRA HETGS X-ray Grating Spectrum of Eta Car
• Why a Single-Star Model Cannot Explain the Bipolar Nebula of Eta Carinae
• A spectroscopic event of eta Car viewed from different directions: The data and first results
• Accretion by the Secondary in Eta Carinae During the Spectroscopic Event: I. Flow Parameters
• Waiting in the Wings: Reflected X-ray Emission from the Homunculus Nebula
• Accretion onto the Companion of Eta Carinae During the Spectroscopic Event: II. X-Ray Emission Cycle
• The Binarity of Eta Carinae and its Similarity to Related Astrophysical Objects
• Accretion-Induced Collimated Fast Wind Model for Eta Carinae

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• Secular Changes in Eta Carinae's Wind 1998-2011
• X-ray Emission from Eta Carinae near Periastron in 2009 I: A Two State Solution
• Eta Carinae's 2014.6 Spectroscopic Event: Clues to the Long-term Recovery from its Great Eruption
• Critical Differences and Clues in Eta Car's 2009 Event
• The Source of the Helium Visible Lines in Eta Carinae
• Using X-Ray Observations to Explore the Binary Interaction in Eta Carinae
• The Orientation of the Eta Carinae Binary System
• Modelling the Radio Light Curve of Eta Carinae
• Modelling the Central Constant Emission X-ray component of eta Carinae
• Accretion onto the Companion of Eta Carinae During the Spectroscopic Event. V. the Infrared Decline
• Accretion onto the Companion of Eta Carinae During the Spectroscopic Event. IV. the Disappearance of Highly Ionized Lines
• A high-velocity transient outflow in Eta Carinae
• N II 5668-5712, a New Class of Spectral Features in Eta Carinae
• The X-ray properties of Eta Carinae during its 2020 X-ray minimum
• The orientation of Eta Carinae and the powering mechanism of intermediate luminosity optical transients (ILOTs)