Constraining the Absolute Orientation of Eta Carinae's Binary Orbit: A 3-D Dynamical Model for the Broad [Fe III] Emission

Abstract

We present a three-dimensional (3-D) dynamical model for the broad [Fe III] emission observed in Eta Carinae using the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS). This model is based on full 3-D Smoothed Particle Hydrodynamics (SPH) simulations of Eta Car's binary colliding winds. Radiative transfer codes are used to generate synthetic spectro-images of [Fe III] emission line structures at various observed orbital phases and STIS slit position angles (PAs). Through a parameter study that varies the orbital inclination i, the PA θ that the orbital plane projection of the line-of-sight makes with the apastron side of the semi-major axis, and the PA on the sky of the orbital axis, we are able, for the first time, to tightly constrain the absolute 3-D orientation of the binary orbit. To simultaneously reproduce the blue-shifted emission arcs observed at orbital phase 0.976, STIS slit PA = +38 degrees, and the temporal variations in emission seen at negative slit PAs, the binary needs to have an i \approx 130 to 145 degrees, θ \approx -15 to +30 degrees, and an orbital axis projected on the sky at a PA \approx 302 to 327 degrees east of north. This represents a system with an orbital axis that is closely aligned with the inferred polar axis of the Homunculus nebula, in 3-D. The companion star, Eta B, thus orbits clockwise on the sky and is on the observer's side of the system at apastron. This orientation has important implications for theories for the formation of the Homunculus and helps lay the groundwork for orbital modeling to determine the stellar masses.

23 pages, 12 color figures, plus 2 online-only appendices (available in the /anc folder of the Source directory). Accepted for publication in MNRAS

References in corpus (50)

• A new calibration of stellar parameters of Galactic O stars
• Physical Properties of Wolf-Rayet Stars
• The evolution of rotating stars
• SPLASH: An interactive visualisation tool for Smoothed Particle Hydrodynamics simulations
• On the role of continuum-driven eruptions in the evolution of very massive stars and Population III stars
• The Structure of the Homunculus: I. Shape and Latitude Dependence from H2 and [Fe II] Velocity Maps of Eta Carinae
• A Porosity-Length Formalism for Photon-Tiring-Limited Mass Loss from Stars Above the Eddington Limit
• In Hot Pursuit of the Hidden Companion of Eta Carinae: An X-ray Determination of the Wind Parameters
• Latitude-dependent effects in the stellar wind of Eta Carinae
• Collisional Ionization Equilibrium for Optically Thin Plasmas. I. Updated Recombination Rate Coefficients for Bare though Sodium-like Ions
• Eta Carinae: Binarity Confirmed
• The periodicity of the eta Carinae events
• 3D modelling of the colliding winds in Eta Carinae - evidence for radiative inhibition
• Detection of Gamma-ray Emission from the Eta-Carinae Region
• A Revised Historical Light Curve of Eta Carinae and the Timing of Close Periastron Encounters
• Spiralling out of control: 3D hydrodynamical modelling of the colliding winds in $\eta$Carinae
• Near-Infrared interferometry of Eta Carinae with high spatial and spectral resolution using the VLTI and the AMBER instrument
• Direct measurement of the size and shape of the present-day stellar wind of Eta Carinae
• Chemical evolution of galaxies. I. A composition-dependent SPH model for chemical evolution and cooling
• High-excitation emission lines near eta Carinae, and its likely companion star
• The UV Scattering Halo of the Central Source Associated with Eta Carinae
• Fermi Large Area Telescope Observation of a Gamma-ray Source at the Position of Eta Carinae
• The Binarity of Eta Carinae Revealed from Photoionization Modeling of the Spectral Variability of the Weigelt Blobs B and D
• Periastron Passage Triggering of the 19th Century Eruptions of Eta Carinae
• The 2003 Shell Event in eta Carinae
• Eta Carinae across the 2003.5 minimum: Spectroscopic Evidence for Massive Binary Interactions
• X-ray Spectral Variation of Eta Carinae through the 2003 X-ray Minimum
• A multispectral view of the periodic events in eta Carinae
• Explosions Triggered by Violent Binary-Star Collisions: Application to Eta Carinae and other Eruptive Transients
• The Early Spectra of Eta Carinae 1892 to 1941 and the Onset of Its High Excitation Emission Spectrum
• Variability of eta Carinae III
• Why a Single-Star Model Cannot Explain the Bipolar Nebula of Eta Carinae
• Wind-Wind Collision in the eta Carinae Binary System: a Shell-Like Event Near Periastron
• 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
• The fragmentation of expanding shells II: Thickness matters
• Critical Differences and Clues in Eta Car's 2009 Event
• Is Eta Carinae a fast rotator, and how much does the companion influence the inner wind structure?
• Comparing Eta Carinae with the Red Rectangle
• The H-alpha Variations of eta Carinae During the 2009.0 Spectroscopic Event
• Using X-Ray Observations to Explore the Binary Interaction in Eta Carinae
• The Source of the Helium Visible Lines in Eta Carinae
• The Eta Carinae optical 2009.0 event, a new "eclipse-like" phenomenon
• The Orientation of the Eta Carinae Binary System
• Wind-wind collision in the Carinae binary system II: Constrains to the binary orbital parameters from radio emission near periastron passage
• Wind-wind collision in the eta Carinae binary system - III. The HeII 4686 line profile
• Models of Forbidden Line Emission Profiles from Axisymmetric Stellar Winds
• Modeling Forbidden Line Emission Profiles from Colliding Wind Binaries
• Constraining the orbital orientation of Eta Carinae from H Paschen lines

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• 3D Printing Meets Computational Astrophysics: Deciphering the Structure of Eta Carinae's Inner Colliding Winds
• VLTI-AMBER velocity-resolved aperture-synthesis imaging of Eta Carinae with a spectral resolution of 12000. Studies of the primary star wind and innermost wind-wind collision
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• Orbital Parameters for the $250M_{\odot }$ Eta Carinae Binary System
• Uncovering the orbital dynamics of stars hidden inside their powerful winds: application to $\eta$ Carinae and RMC 140
• Eta Carinae's Thermal X-ray Tail Measured with XMM-Newton and NuSTAR
• AU-scale radio imaging of the wind collision region in the brightest and most luminous non-thermal colliding wind binary Apep
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• 3D radiative transfer simulations of Eta Carinae's inner colliding winds - II: Ionization structure of helium at periastron
• Near-Infrared Evidence for a Sudden Temperature Increase in Eta Carinae
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• The X-ray properties of Eta Carinae during its 2020 X-ray minimum
• The environment of the wind-wind collision region of $\eta$ Carinae
• NICER X-ray Observations of Eta Carinae During its Most Recent Periastron Passage
• The Interaction of the Eta Carinae Primary Wind with a Century Old Slow Equatorial Ejecta
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• Resolving the H-alpha-emitting Region in the Wind of Eta Carinae
• Interacting winds in massive binaries
• The bright, dusty aftermath of giant eruptions & H-rich supernovae. Late interaction of supernova shocks & dusty circumstellar shells
• A Case Study in Astronomical 3-D Printing: The Mysterious Eta Carinae
• GRAVITY chromatic imaging of Eta Car's core
• Detection of very-high-energy gamma-ray emission from Eta Carinae during its 2020 periastron passage
• Probing cosmic ray escape from η Carinae
• Numerical simulations of wind-equatorial gas interaction in eta Carinae
• The orientation of Eta Carinae and the powering mechanism of intermediate luminosity optical transients (ILOTs)
• 3-D structures of planetary nebulae
• Telluric absorption lines in the ALMA spectra of $\eta$ Car
• Limits on the non-thermal emission of the WR-WR system Apep
• Gamma-rays and positrons from Colliding Wind Binaries
• Eta Carinae: an evolving view of the central binary, its interacting winds and its foreground ejecta