A 3D Fly Through of a Supernova

I was at the AAS meeting last week and had little time to blog. Lots of cool results were announced. My favorite is a 3d fly though of the supernova remnant Cas A. This supernova blew up a little over 300 years ago and is one of the brightest radio sources in the sky and one of the closest and youngest supernova remnants making it a prime target for observing.

Only large stars can go supernova. This star probably had about 10 times the mass of our Sun. When it runs out of fuel, its core collapses to a neutron star. A neutron star, as its name implies, is made entirely of neutrons as the protons and electrons get crushed together and form neutrons (plus neutrinos, but they escape the star). The outer layers of the star star to collapse. As the neutrinos encounter the collapsing gas, a huge shock wave forms blowing the star apart. It's pretty complicated, but that's the basic picture (and the detials aren't entirely understood!)

The outer layers of the star contain a wide variety of elements: helium, oxygen, neon, carbon and silicon among others. The added energy from the shock wave can fuse these elements to from gold, silver and, well, all the elements heavier than iron!

So how do we make this 3d fly through? The supernova remnant is 3 dimensional. We can see it expanding. Pieces that move at right angles to our line of site appear to move the quickest across the sky. Pieces coming straight toward or away from us appear not to move at all. For the pieces that appear to move slowly, we use doppler shifts to tell whether they are moving toward or away from us. We combine data from the Chandra X-Ray telecope, the Spitzer Space Telescope (which observes in infared) and ground based optical telescopes, run it through a program called 3D slicer, and you get this.



The little neutron star at the center is about 6 miles wide and has about 1.4 times the mass of our Sun. It rotates dozens of times a second (its rotations speeds up when it collapses similar to a figure skater pulling in her arms and spinning faster).

Fortunately, this was about 10,000 light years away because we don't want one of these blowing up near us!

Reprinted with permission from the Half-Astrophysicist Blog.