We can take a moment to admire the star. We can do it from a distance of 7,500 light years. I don't think we would want to be too close to each other.
It is one of the scariest stars in the sky. It is a pair of stars, two of which are beasts. One is 50 times the mass of the Sun, a huge powerhouse that would dwarf everything else in the universe.
The amount of energy a star gives off is very sensitive to its mass, and it is right next to one that has at least a hundred times the Sun's mass. The primary is at least a million times brighter than the Sun.
One. There is a million. The times. At least.
That is not the reason I am happy it is far away.
The primary erupted in an event so large it was just this side of a supernova. Over time, the blast of matter and energy launched something like 20 times the mass of the Sun into space. The material has been expanding ever since, forming a pair of lobes. There is material farther out from the star.
It is difficult to untangle and understand the complex and beautiful structure around Eta Carinae.
But not impossible! Using observations that span the spectrum from IR to X-rays using Hubble, the team of artists created a stunning 3D animation of Eta Carinae, showing models of what it looks like in these different wavelengths. You can watch:
Whoa.
The structure is called the Humonculus Nebula. Stars that blow out gas have this sort of figure. It means there is a dense disk of material around the equator, and when the gas gets blown out it has a harder time moving in the direction of the equator.
There is evidence of a disk in the observations, which may have arisen from interactions between the primary and secondary stars. It is possible that the primary star is a rapid rotator, spinning on its axis so quickly that material is flung away along its equator.
The overall shape of the lobes is formed by the red glow of the hydrogen and nitrogen blasted out in the eruption. In the video, the two stars are bright in ultraviolet light. Some of this is ionized magnesium, which was blasted out in the eruption and glows in the UV.
This fierce light shines through gaps in the disk material closer in, creating beams of light called crepuscular rays, the same phenomena you see when the Sun shines light through clouds.
The material ejected from earlier episodes is glowing red again. Outside of that is a cloud of material that emits high-energy light. The X-rays may be due to the powerful shock waves created by the material slamming into the gas at a greater distance from the stars.
The X-rays are very close to the stars. The secondary star is on an elliptical path that takes it from a distance of 4.5 billion kilometers to only 250 million kilometers. Both stars emit X-rays when they collide with each other. The emission is seen to wax and wane on a cycle that takes the stars to circle each other.
The video doesn't show the light emitted by the dust around the system. The light from the stars is absorbed by the dust, which warms it up enough to glow in the IR. There is so much dust and so much energy in the sky that it is the most bright source in the sky.
When I worked on the Hubble instrument, I got headaches every time I looked at the Eta Carinae spectrum. They were a mess, a mess of emission from a dozen different tortured elements like hydrogen, nitrogen, and iron, flung around at such high speed. It was difficult to understand them.
But worth it! The physics of how stars behave is not understood. We know that stars that large are prone to be unstable. The star's core is so massive that it can suddenly jump in rate and cause a domino effect, as the star's upper layers are so energetic that it can barely hold on to them.
One thing we know for certain is that Eta Carinae won't last long. Less than a million years from now, the core of the mighty star will run out of fuel. The star will collapse and the outer layers of it will explode. It will probably go supernova, blowing out enough energy to dwarf the entire Milky Way galaxy. It will be more brilliant than Venus in our night sky.
I am glad we are 7,500 light years away. Close enough to study it and try to understand it, but far enough away that we don't get burned by it. I think that is a good compromise.
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