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- Volume 80 - Année 2011
- Constraining the Properties of the Eta Carinae System via 3-D SPH Models of Space-Based Observations: The Absolute Orientation of the Binary Orbit
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Constraining the Properties of the Eta Carinae System via 3-D SPH Models of Space-Based Observations: The Absolute Orientation of the Binary Orbit
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Annexes
Abstract
The extremely massive (> 90 Mo) and luminous (= 5 × 106 Lo) star Eta Carinae, with its spectacular bipolar “Homunculus” nebula, comprises one of the most remarkable and intensely observed stellar systems in the Galaxy. However, many of its underlying physical parameters remain unknown. Multiwavelength variations observed to occur every 5.54 years are interpreted as being due to the collision of a massive wind from the primary star with the fast, less dense wind of a hot companion star in a highly elliptical (e ~ 0.9) orbit. Using three-dimensional (3-D) Smoothed Particle Hydrodynamics (SPH) simulations of the binary windwind collision, together with radiative transfer codes, we compute synthetic spectral images of [Fe III] emission line structures and compare them to existing Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) observations. We are thus able, for the first time, to tightly constrain the absolute orientation of the binary orbit on the sky. An orbit with an inclination of i ~ 40°, an argument of periapsis omega ~ 255°, and a projected orbital axis with a position angle of ~ 312° east of north provides the best fit to the observations, implying that the orbital axis is closely aligned in 3-D space with the Homunculus symmetry axis, and that the companion star orbits clockwise on the sky relative to the primary.
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A propos de : Thomas I. Madura
University of Delaware, Newark, DE, USA
A propos de : Theodore R. Gull
NASA Goddard Space Flight Center, Greenbelt, MD, USA
A propos de : Stanley P. Owocki
University of Delaware, Newark, DE, USA
A propos de : Atsuo T. Okazaki
Hokkai-Gakuen University, Sapporo, Japan
A propos de : Christopher M.P. Russell
University of Delaware, Newark, DE, USA