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Thomas I. Madura, Theodore R. Gull, Stanley P. Owocki, Atsuo T. Okazaki & Christopher M.P. Russell

Constraining the Properties of the Eta Carinae System via 3-D SPH Models of Space-Based Observations: The Absolute Orientation of the Binary Orbit

(Volume 80 - Année 2011)
Article
Open Access

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.

To cite this article

Thomas I. Madura, Theodore R. Gull, Stanley P. Owocki, Atsuo T. Okazaki & Christopher M.P. Russell, «Constraining the Properties of the Eta Carinae System via 3-D SPH Models of Space-Based Observations: The Absolute Orientation of the Binary Orbit», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 80 - Année 2011, 694 - 698 URL : https://popups.ulg.ac.be/0037-9565/index.php?id=3158.

About: Thomas I. Madura

University of Delaware, Newark, DE, USA

About: Theodore R. Gull

NASA Goddard Space Flight Center, Greenbelt, MD, USA

About: Stanley P. Owocki

University of Delaware, Newark, DE, USA

About: Atsuo T. Okazaki

Hokkai-Gakuen University, Sapporo, Japan

About: Christopher M.P. Russell

University of Delaware, Newark, DE, USA