Accretion onto the Companion of Eta Carinae During the Spectroscopic Event. IV. the Disappearance of Highly Ionized Lines

Abstract

We show that the rapid and large decrease in the intensity of high-ionization emission lines from the Eta Carinae massive binary system can be explained by the accretion model. These emission lines are emitted by material in the nebula around the binary system that is being ionized by radiation from the hot secondary star. The emission lines suffer three months long deep fading every 5.54 year, assumed to be the orbital period of the binary system. In the accretion model, for ~70 day the less massive secondary star is accreting mass from the primary wind instead of blowing its fast wind. The accretion event has two effects that substantially reduce the high-energy ionizing radiation flux from the secondary star. (1) The accreted mass absorbs a larger fraction of the ionizing flux. (2) The accreted mass forms a temporarily blanked around the secondary star that increases its effective radius, hence lowering its effective temperature and the flux of high energy photons. This explanation is compatible with the fading of the emission lines at the same time the X-ray is declining to its minimum, and with the fading being less pronounced in the polar directions.

ApJ, in press

References in corpus (7)

• Radio, X-ray, and gamma-ray Emission Models of the Colliding Winds Binary WR 140
• The UV Scattering Halo of the Central Source Associated with Eta Carinae
• The Chrysalis Opens? Photometry from the Eta Carinae HST Treasury Project, 2002-2006
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• Accretion onto the Companion of Eta Carinae During the Spectroscopic Event: III. the He II 4686 Line
• Resonance-Enhanced Two-Photon Ionization (RETPI) of SiII and an Anomalous, Variable Intensity of the 1892A SiIII] Line in the Weigelt Blobs of Eta Carinae
• Variable Unidentified Emission Near 6307 AA in Eta Carinae

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