Wind-wind collision in the eta Carinae binary system - III. The HeII 4686 line profile

Abstract

We modeled the HeII 4686 line profiles observed in the eta Carinae binary system close to the 2003.5 spectroscopic event, assuming that they were formed in the shocked gas that flows at both sides of the contact surface formed by wind-wind collision. We used a constant flow velocity and added turbulence in the form of a gaussian velocity distribution. We allowed emission from both the primary and secondary shocks but introduced infinite opacity at the contact surface, implying that only the side of the contact cone visible to the observer contributed to the line profile. Using the orbital parameters of the binary system derived from the 7 mm light curve during the last spectroscopic event (Paper II) we were able to reproduce the line profiles obtained with the HST at different epochs, as well as the line mean velocities obtained with ground based telescopes. A very important feature of our model is that the line profile depends on the inclination of the orbital plane; we found that to explain the latitude dependent mean velocity of the line, scattered into the line of sight by the Homunculus, the orbit inclination should be close to 90 degrees, meaning that it does not lie in the Homunculus equatorial plane, as usually assumed. This inclination, together with the relative position of the stars during the spectroscopic events, allowed us to explain most of the observational features, like the variation of the Purple Haze with the orbital phase, and to conciliate the X-ray absorption with the postulated shell effect used to explain the optical and UV light curves.

arXiv commentto appear in the MNRAS

References in corpus (18)

• The Structure of the Homunculus: I. Shape and Latitude Dependence from H2 and [Fe II] Velocity Maps of Eta Carinae
• Latitude-dependent effects in the stellar wind of Eta Carinae
• Eta Carinae: Binarity Confirmed
• The UV Scattering Halo of the Central Source Associated with 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?
• The Departure of Eta Carinae from Axisymmetry and the Binary Hypothesis
• A Change in the Physical State of $\eta$ Carinae?
• The formation of stars in groups
• Eta Carinae's Brightness Variations Since 1998: HST Observations of the Central Star
• A spectroscopic event of eta Car viewed from different directions: The data and first results
• Wind-Wind Collision in the eta Carinae Binary System: a Shell-Like Event Near Periastron
• Millimeter-wave emission during the 2003 low excitation phase of eta Carinae
• VLT-UVES observations of the Balmer line variations of eta Carinae during the 2003 spectroscopic event
• Wind-wind collision in the Carinae binary system II: Constrains to the binary orbital parameters from radio emission near periastron passage
• Time variations of the narrow FeII and HI spectral emission lines from the close vicinity of Eta Carinae during the spectral event of 2003
• Large Scale Structure in the ELAIS S1 Survey
• Modelling spectral line profiles of wind-wind shock emissions from massive binary systems

Cited by in corpus (18)

• Spiralling out of control: 3D hydrodynamical modelling of the colliding winds in $\eta$Carinae
• Constraining the Absolute Orientation of Eta Carinae's Binary Orbit: A 3-D Dynamical Model for the Broad [Fe III] Emission
• Constraints on decreases in Eta Carinae's mass loss from 3D hydrodynamic simulations of its binary colliding winds
• He II $\lambda$4686 emission from the massive binary system in $\eta$ Car: constraints to the orbital elements and the nature of the periodic minima
• Chandra X-ray Grating Spectrometry of Eta Carinae near X-ray Minimum: I. Variability of the Sulfur and Silicon Emission Lines
• He II 4686 in eta Carinae: collapse of the wind-wind collision region during periastron passage
• Detection of high-velocity material from the wind-wind collision zone of Eta Carinae across the 2009.0 periastron passage
• MHD numerical simulations of colliding winds in massive binary systems - I. Thermal vs non-thermal radio emission
• Eta Carinae's 2014.6 Spectroscopic Event: Clues to the Long-term Recovery from its Great Eruption
• The Orientation of the Eta Carinae Binary System
• Orbital Parameters for the $250M_{\odot }$ Eta Carinae Binary System
• Constraining the orbital orientation of Eta Carinae from H Paschen lines
• The X-ray properties of Eta Carinae during its 2020 X-ray minimum
• $\eta$ Carinae: high angular resolution continuum, H30$\alpha$ and He30$\alpha$ ALMA images
• The Interaction of the Eta Carinae Primary Wind with a Century Old Slow Equatorial Ejecta
• Numerical simulations of wind-equatorial gas interaction in eta Carinae
• Precession and Nutation in the eta Carinae binary system: Evidences from the X-ray light curve
• The orientation of Eta Carinae and the powering mechanism of intermediate luminosity optical transients (ILOTs)