The three-dimensional structure of the Eta Carinae Homunculus★

Abstract

We investigate, using the modeling code SHAPE, the three-dimensional structure of the bipolar Homunculus nebula surrounding Eta Carinae as mapped by new ESO VLT/X-Shooter observations of the H 2 λ = 2.12125µm emission line. Our results reveal for the first time important deviations from the axisymmetric bipolar morphology: 1) circumpolar trenches in each lobe positioned point-symmetrically from the center and 2) off-planar protrusions in the equatorial region from each lobe at longitudinal (∼ 55 • ) and latitudinal (10 • − 20 • ) distances from the projected apastron direction of the binary orbit. The angular distance between the protrusions (∼ 110 • ) is similar to the angular extent of each polar trench (∼ 130 • ) and nearly equal to the opening angle of the wind-wind collision cavity (∼ 110 • ). As in previous studies, we confirm a hole near the centre of each polar lobe and no detectable near-IR H 2 emission from the thin optical skirt seen prominently in visible imagery. We conclude that the interaction between the outflows and/or radiation from the central binary stars and their orientation in space has had, and possibly still has, a strong influence on the Homunculus. This implies that prevailing theoretical models of the Homunculus are incomplete as most assume a single star origin that produces an axisymmetric nebula. We discuss how the newly found features might be related to the Homunculus ejection, the central binary and the interacting stellar winds.

3D printing meets computational astrophysics: deciphering the structure of η Carinae's inner colliding winds

“…In the 1840s, η Car became the second brightest non-solar-system object in the sky and ejected between 10 and 40 M , forming the dusty bipolar "Homunculus" nebula (Smith et al 2003;Gomez et al 2010;Steffen et al 2014). Amazingly, this did not destroy the star(s).…”

“…1 from Vogt et al (2014) (see their fig. 15) and a 3D printable version of the Eta Carinae Homunculus nebula model by Steffen et al (2014) 2 . Each of these is a unique illustration of how observational data can be used to develop a 3D printable model for increased understanding and communication of complex concepts.…”

AstroBlend: An astrophysical visualization package for Blender

“…The largest of the three isosurfaces depicted in Figure 8 has also been made available as a 3D-printable file on Thingiverse 25 , a repository for freely available three dimensional printing model files. OBJ files exported from Blender can be uploaded into many open source 3D printing software packages, which can then be configured to print on specific 3D printers [13,14,16]. In Figure 9, the original isosurface is shown alongside a photograph of its 3D-printed version.…”

“…Recent innovations in the computer graphics and gaming industry can be exploited for this multi-pronged approach to data investigation [5,11]. In addition to increasing the rate of information exchange within scientific collaborations, as technological advancements in graphics and gaming progress, innovative methods for discussing scientific concepts with the general public can be developed [12,13,14,15,16].…”

Axisymmetric outflows from binary point-source systems in the presence of an interface

“…This nebula consists of dust and ejected gas, forming two large osculating spheres such that the overall structure is approximately axisymmetric. A model that accounts for some features of the 'Great Eruption' of 1844 has been advanced by Smith (2013), and further details about the bipolar homunculus nebula and its composition are given by Steffen et al (2014). After some debate in the literature, the consensus is now that the Eta Carinae object most likely consists of two stars, one of about 110 M and the other of perhaps 30 M .…”