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Ted Gull: Eta Carinae is one of the most

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intriguing sources in the sky. And there's actually a large group of us

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around the world that are keenly interested in it.

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Tom Madura: Eta Carinae is one of the most massive stars in the galaxy, and it is also

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a very evolved massive star that we think is near the end of its

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lifetime. It is believed to be about 90 solar

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masses, and it was thought to be a single star star for the longest time,

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but it turns out that we know that it is actually a binary system and there is a second

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star that we believe to be about 30 solar masses that exists

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in the system. In the 1840s, Eta Carinae

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experienced what we call the "Great Eruption" where it blew out somewhere between

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10 and 40 times the mass of our sun in material.

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And that material formed this nebula that now surrounds the system.

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Ted: The nebula itself is a little bit large to map completely by Hubble,

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and actually we did that a long time ago with the Space Telescope Imaging Spectrograph

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However, we were only able to see evidence of the

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dust, dusty regions. Tom: So, the thing that we did is

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we had a international collaboration, and we used the

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Very Large Telescope, in Chile, to do

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spectroscopic mapping of the entire Homunculus Nebula, and what makes

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our mapping unique is that previously only about

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five slits had been used to map the entire Homunculus

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whereas we used closer to 100 slits across the entire

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length of the nebula to map everything including very small details.

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This is one of the first times we not only have a

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3D model for an astrophysical object. but we were actually able to take our

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3D model and print it on a 3D printer.

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Ted: What we find here is that there's dimples in the two lobes:

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here in the blue shifted--that which is approaching us--and in the red shifted

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section here. And then most peculiarly, in between,

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where we might expect to see something fairly symmetrical around here, we see

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these two wings coming out, tilted both with respect to the

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bi-polar structure and with respect to the orbit of the two stars.

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Tom: That gives us very important information

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about the physical mechanisms that are responsible for forming the

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nebula. For example: trying to determine whether or not it was a single

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star that had an explosion, or if the binary had some

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important effect on shaping the nebula. Ted: This new model tells

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us that, potentially, the explosive event happened

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when the stars were closest to each other, and that

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the material that came out not only came out in the polar regions

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but was shaped in the orbital plane, which is between

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these two systems. It tells us that the explosion event

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probably started on one side of the star and then propagated elsewhere.

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Tom: Prior to these observations and the modeling, there was no

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reason to think that binarity played any role

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in the eruption or the forming and shaping of the homunculus.

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But now that we have this more detailed model, it turns out that the

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distance between each of these features is very similar to

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measurements of the central binary, and so for the first time,

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we have evidence that binarity played a role

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either in the Great Eruption itself, or in shaping

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the nebula after the initial explosion.

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